Aqualung already answered this, but I'm just going to go ahead and respond to your next question before you ask it, if that's okay.
Merlin: Reformed Eqyptian? What the ___ is that?
Kathryn: The Book of Mormon itself provides the answer to that question. Mormon 9:32-34 states,
"And now, behold, we have written this record according to our knowledge, in the characters which are called among us the reformed Egyptian, being handed down and altered by us, according to our manner of speech. And if our plates had been sufficiently large we should have written in Hebrew; but the Hebrew hath been altered by us also; and if we could have written in Hebrew, behold, ye would have had no imperfection in our record. But the Lord knoweth the things which we have written, and also that none other people knoweth our language; and because that none other people knoweth our language, therefore he hath prepared means for the interpretation thereof."
So, in essence, the oral language was Hebrew, but the written language was a modified form of the Egyptian language. It was used primarily to conserve space, as time frame covered was roughly 1000 years.