The word in the original Hebrew text is "satan", meaning adversary.
"And the day is, that sons of God come in to station themselves by Jehovah, and there doth come also the Adversary in their midst." (Job 1:6, YLT)
Strong's Heb. 7853, of uncertain derivation, an adversary, or opponent; one who withstands or stands against another; late Hebrew to "be remote, especially from the truth, and from the mercy of God;" (Source: Biblehub)
The Bible does not directly state the reason for the adversary's appearance at this meeting. But we know that the adversary was always intent upon causing man (adam) to stumble and turn away from God. This was his purpose against Job, to try to cause Job to turn from God.
God asked the adversary two questions that are telling.
"And Jehovah saith unto the Adversary,
Whence comest thou?'... And Jehovah saith unto the Adversary, Hast thou set thy heart against My servant Job because there is none like him in the land, a man perfect and upright, fearing God, and turning aside from evil?'" (Job 1: 7-8, YLT)
The adversary was not an "angel". The word transliterated as "angel" in the scriptures was from the Gr. "aggelos" and simply means a messenger, or envoy; one who was sent. (Source: Biblehub) The translators determined when to use the word "angel" or when to actually translate it as "messenger". They should have been consistent in using "messenger", but they read their belief systems into their translations.
Further, there is a misunderstanding being taught that the "sons of God" in Job 1:6, and Job 38:7 are "angels". Neither verse uses the word for "angel". These are not messengers. The "sons of God" used in these verses are something else. We know this from Hebrews.
"For unto which of the angels said he at any time, Thou art my Son,..." (Heb. 1:5, KJV)
"For to which of the messengers said He ever, 'My Son thou art..." (Heb. 1:5, YLT)
We also must consider Paul's statement in Romans.
"13 for if according to the flesh ye do live, ye are about to die; and if, by the Spirit, the deeds of the body ye put to death, ye shall live; 14 for as many as are led by the Spirit of God, these are the sons of God;" (Rom. 8:13-14, YLT)
The "sons of God" are those led by the Spirit of God. God's does not change (Mal. 3:6; Num. 23:19; Psa. 102:25-27; Heb. 13:8). Therefor, the use of the phrase "sons of God" in Job is not "angels". While most translations say "sons of God', a better sense is given as "heavenly beings" in the GNT, and the NRSVA. Not all of the heavenly host are "angels" / messengers.
Further, the pagan mythology of fallen angels is slandering the heavenly, celestial messengers who always brought the truth of God's word to men.
"20 Bless Jehovah, ye His messengers, Mighty in power -- doing His word, To hearken to the voice of His Word." (Psa. 103:20, YLT)
It is better to broaden our thinking about these heavenly beings spoken of in Job.
See more at ShreddingTheVeil.org:
Testing the Spirits - Part IV (a): Slandering Angels here
Testng the Spirits - Part IV (b): here