Someone is telling me that the Bible is inaccurate for the reason that ancient Hebrew (specifically the dialect of Hebrew that the Torah was written in) is a lost language and nobody knows anything about it, therefore the translators of the Bible made guesses on what the ancient Hebrew words meant without having anything to compare the texts to. They compared the writings of ancient Torah texts to hieroglyphics, in that we don't know anything about their meaning. I'm curious to know what the process is behind deciphering the texts, and was wondering if someone could go in detail for me. I'm only able to find articles confirming the reliability of the texts, and that they are almost exactly the same today as they were when they were written. Are these person's claims correct?
Lexicons are important because, as wikipedia says
Linguistic theories generally regard human languages as consisting of two parts: a lexicon, essentially a catalogue of a language's words (its wordstock); and a grammar, a system of rules which allow for the combination of those words into meaningful sentences. The lexicon is also thought to include bound morphemes, which cannot stand alone as words (such as most affixes). In some analyses, compound words and certain classes of idiomatic expressions and other collocations are also considered to be part of the lexicon.
So, Hebrew lexicons often provide lists of citations of examples and references for the usage and gloss of a given word. This, added to the fact that Hebrew is spoken today allow for linguists to do much analysis and understand Biblical Hebrew surprisingly well - similar to what we are able to do with early English writings.
This can be a bit of a challenge in the case of hapax legomenon, which is a word or an expression that occurs only once within a context. (but there are only about 400 occurrences of these out of 8,679 distinct words used in the Torah...)
One of the most significant ways Hebrew linguists are able to cross-check the meanings of Hebrew words of Antiquity (including their best guesses of translations of hapax legomenon) is using the Septuagint. This body of work was an attempt by Jewish scholars beginning in the 3rd century BCE to translate the Torah into Koine Greek. This dates to with a few decades of the writing of Chronicles (which includes 1st and 2nd kings) Ezra-Nehemiah, Esther and others. Daniel was probably penned after the Septuagint was started.
Interestingly, you can even see how translation issues evident in the Septuagintal translations influence New Testament works. For example, "young woman" was often translated to "virgin" in Greek, which gets a bit odd when in Genesis 34:3, the Septuagint refers to Dinah as a "virgin" immediately after her rape. Similarly, some think this may be the reason for the Virgin Birth of Jesus: the Old Testament prophesy simply said the Messiah was going to be born to a "young woman" but many Jews may have thought that the Messiah was to be born of a virgin specifically because of the Greek rendering.
Because our understanding of Koine Greek is fairly mature, the Septuagint allows modern scholars to cross-check and fine tune their translations into English by comparing them against translations made by native speakers during the era that many of these works were written. It does also bring a cadre of problems and challenges and causes innumerable debates and discussion with many levels of pedantry, but is also part of what makes Biblical translation a fascinating field of study. Most scholars would agree that while translators don't always get it "right" they are pretty darn close most of the time.
If this kind of thing is of interest to you, one interesting work is the NET Bible which includes detailed translators' notes about how and why many English renderings were made.
The Open English Bible also attempts this feat as well.