The question is to two words. This answer addresses only (et).
As noted in the first answer that (et) is the untranslatable mark of the accusative case. Strong’s Concordance says it is apparently a contraction of (#226) in the demonstrative sense of entity; properly self (but generally used to point out more definitely the object of a verb or preposition, even or namely). I understand it as a device to point to something. According to the Englishman’s concordance at Bible Hub (et) occurs 7034 times: http://biblehub.com/hebrew/et_853.htm
While not translated the meaning can be studied like any word and a good way to start is to see how it is used. The question is over the meaning in Genesis 1:1 which is also the first use. The usage can be followed through the seven days of creation noting where it is used and what comes before and after:
It is used most often after the word God (Elohim). From the perspective of the days of creation the most frequent use is on the sixth day where it is found 6 times. There is a single use on the seventh day, meaning that the final seven usages fall into the form of a Sabbath pattern. There are seven; the first six have something in common and the seventh can be set apart. A similar arrangement can be seen in the first seven usages, except the pattern has been reversed. The first use in Genesis 1:1 comes before the first day and the next six are during the days of creation. Another thing that stands out is the absence of use on the third day.
These patterns suggest intentional arrangement within the overall written account. If that is the case, the understanding of the word should not be viewed in a limited sense of pointing to another word or words. Rather it is also pointing to the overall architecture of the creation account. In this sense (et) is a means of connecting the entire seven days of creation.
Creation events are also found after the seventh day and the usage can be followed in the remainder of Genesis 2:
It is used 10 times and there is no obvious connection to the previous patterns. While numerology can be overvalued, it should not be completely discounted. There are some obvious connections with the number 10 and God’s work to redeem mankind. Ten is the number of generations before the flood; there were 10 plagues before the Exodus; there were Ten Commandments. Ten is considered a number signifying perfection which is consistent with the how the written record describes the events up to this point, where the man and the woman are together in the garden with the LORD God. There has been no disobedience.
If the text is taken literally, the first use in this second record of creation events can be placed on the third day. When that is done, the use of (et) provides a means of connecting the two creation accounts:
And God said, Let the waters under the heaven be gathered together unto one place, and let the dry land appear: and it was so. And God called the dry land Earth; and the gathering together of the waters called he seas: and God saw that it was good. (Genesis 1:9-10 KJV)
These are the generations of the heavens and of the earth when they were created, in the day that the LORD God made the earth and the heavens, And every plant of the field before it was in the earth, and every herb of the field before it grew: for the LORD God had not caused it to rain upon the earth, and there was not a man to till (et) the ground. But there went up a mist from the earth, and watered (et) the whole face of the ground. (Genesis 2:4-6 KJV)
And God said, Let the earth bring forth grass, the herb yielding seed, and the fruit tree yielding fruit after his kind, whose seed is in itself, upon the earth: and it was so. And the earth brought forth grass, and herb yielding seed after his kind, and the tree yielding fruit, whose seed was in itself, after his kind: and God saw that it was good. And the evening and the morning were the third day. (Genesis 1:11-13 KJV)
The (et) locates where the record in Genesis 2 should be inserted into the events of the third day. This not only adds what had been absent in the description of the first seven days, it makes the reading of the third day more complete: there was no man, there was no rain, there was a mist from the earth, God said let the earth bring forth grass yielding seed.
There are 3 other uses of (et) in the Genesis 2 record which can be placed on the third day:
And God said, Let the earth bring forth grass, the herb yielding seed, and the fruit tree yielding fruit after his kind, whose seed is in itself, upon the earth: and it was so. And the earth brought forth grass, and herb yielding seed after his kind, and the tree yielding fruit, whose seed was in itself, after his kind… (Genesis 1:11-12 KJV)
And a river went out of Eden to water (et) the garden; and from thence it was parted, and became into four heads. The name of the first is Pison: that is it which compasseth (et) the whole land of Havilah, where there is gold; And the gold of that land is good: there is bdellium and the onyx stone. And the name of the second river is Gihon: the same is it that compasseth (et) the whole land of Ethiopia. And the name of the third river is Hiddekel: that is it which goeth toward the east of Assyria. And the fourth river is Euphrates. (Genesis 2:10-14 KJV)
…and God saw that it was good. And the evening and the morning were the third day. (Genesis 1:12-13 KJV)
In Genesis 2, the rivers are described in the context of the Garden of Eden which would be planted on the sixth day and where the man would be placed. The physical reality is that those rivers were already in existence; they had been created on the third day; not just the rivers, the precious metals and stones were also created on the third day.
The rivers and the garden have a common physical element: location. Yet the plants in the garden are not the source of the water for the rivers (if the rivers are taken as real rivers) nor was the garden planted on the third day. The (et) has been used with the rivers (created on the third day) but also defined by proximity to Eden and the garden (hence their placement in the second record).
The description of the four rivers has been puzzling as the location of the Pishon and Gihon is uncertain. The (et) is present in describing the two unknown rivers and it is missing from Tigris and Euphrates (whose locations are known). This seems to be an intentional device.
This pattern of usage has the effect of reinforcing the intentional use of (et) in the first record of seven days. Had the third day use been placed in the first record, there would be no pattern of sevens. Also there are six uses which can be placed on the sixth day, a repetition of the pattern in the first account. The six uses are broken up by the description of the rivers and which continues the pattern of where the (et) is present and where it is absent.
Following creation is the fall of man. Here is the use of (et) in Genesis 3:
There are seven uses. The first one is unique in that (et) occurs before both Elohim (and YHVH). This reverse of position in relation to Elohim makes this use unique following the pattern of the first use in Genesis 1:1. As with the first two records (et) is noticeable by it absence: there is no use of (et) as it pertains to the woman. The use and absence of (et) from common elements in the three records are:
First record Missing from third day
Second record Missing from two rivers
Third record Missing from one of two people
There is a pattern of declining numbers: third day, two rivers, one person.
The uses in Genesis 3 can be divided at the expulsion from the garden. The last three occur in 3:24 which detail the expulsion and the steps taken to prevent their return. The uses at the beginning of Genesis 3 can be combined with the Genesis 2 record:
There are 14 uses, the same number found in the first seven days and the first and last use contain the identical phrase:
And every plant of the field before it was in the earth, and every herb of the field before it grew: for the LORD God had not caused it to rain upon the earth, and there was not a man to till (laabod) (et) the ground (haadamah). (Genesis 2:5 KJV)
Therefore the LORD God sent him forth from the garden of Eden, to till (laabod) (et) the ground (haadamah) from whence he was taken. (Genesis 3:23 KJV)
The conclusion is that (et) is being used in such a way that ties together all three written records and does so using patterns found in the actual events. For example, there are 2 sets of six uses on the sixth day; there are two sets of 14 where the first and last uses can be set apart from. (14 is the number needed to establish the Sabbath – 7 days of creation and 7 days to the Sabbath.) The (et) is being used in a way that goes beyond a definition of a word.
This usage reflects single authorship and deliberate intent to use the mark in a way which also follows a message.
First 7 – Points to the pre-existent one
Second 7 – Points to the Sabbath
Third 10 – Points to the initial perfect of what was created
Fourth 7 – Points again to the pre-existent one
Also if (et) has meaning independent of Elohim, it would result in a different understanding of those verses where it is used without Elohim:
And God said, Behold, I have given you every herb bearing seed, which is upon the face of all the earth… (Genesis 1:29 KJV) becomes: And God said, Behold, I have given (et) every herb bearing seed, which is upon the face of all the earth…
You is not in the Hebrew, (et) is.
Given the use my conclusion is that the meaning of (et) is that it is another way in the Hebrew language to identify the Creator.
In speaking there is the unpronounceable name of God: YHVH. In writing there is the untranslatable name of God: (et). While untranslatable, it can be spoken. The letters (et) are Aleph Tav, the first and last letters of the Hebrew language.