The Bible does not tell us what language Adam and Eve spoke. The only hint we get is when Adam called his wife “woman” because she was taken “out of man” (Genesis 2:23). The Hebrew word for “man” is ish and the Hebrew word for “woman” is ishah. But, before concluding that Adam and Eve spoke Hebrew because of this word play, we should also note that there is similar word play in English: man and woman are similar words. It is also possible that in Genesis Moses is simply giving a Hebrew equivalent of whatever language they spoke, just as English versions give an English equivalent.
Another clue is found in Genesis 3:20: “The man named his wife Eve, because she was the mother of all the living.” In Hebrew, the word for “Eve” and the word for “living” have a similar sound. There is no equivalent in English. The English word Eve sounds more like the end of something than the beginning. However, our word Eve is from the Latin Eva, which sounds somewhat similar to the Hebrew word havvah, which sounds somewhat similar to the Hebrew word for “live.”
We really have no idea what language Adam and Eve spoke. The evidence in Genesis can easily be explained as a Hebrew translation of whatever the original language was. We should also remember that the languages were confused at Babel, and the “original language” may have been lost there (Genesis 11). Even if the original language was some form of what we know today as Hebrew or some other Semitic language, languages change over time. Fluent English speakers often have trouble with Shakespeare’s Elizabethan English, barely 400 years old, not to mention Chaucer’s Middle English, barely 150 years older than that. And the Old English of Beowulf, written some 350 years before Chaucer, is hardly recognizable as English at all and must be translated to be understood by today’s readers. It is most likely that whatever language Adam and Eve spoke is completely lost to us today, even if it eventually morphed into what was called Hebrew at the time of Moses.