Rashi to Devarim 1:5 says Moshe translated the Torah into 70 languages. Why did he do so?
The Kesav Sofer answers that there were people who where saying that the Torah is only for when we are amongst ourselves, in the desert, or in Eretz Yisroel.Therefore before they entered Eretz Yisroel it was written in all the languages. Telling the Jews no matter where you go, and no matter what language you speak, the Torah applies in all of them. The Kedushas Levi points out here that the Torah has many foreign words from the african language to the Greek language, he says that is because the source for the foreign nations are on High and in order for them to exsist on the physical plane the must exsist on the metaphysical plane in the torah. He takes the original point one step further and says the Jews born out of Israel will see that there native language is in the torah and this will be a source of encouragment for them as they will see somthing to identify with.
The Ksav Vhakabalah has a completly diffrent approach He says the Seventy languages taught here are the equivlant of the language of the Gemara of Lishnah Achrinah that is a diffrent Pshat that Moshe taught the Jews that there are 70 ways to learn the torah and it is not the one is wrong or right and that was important at this point as he was leaving and this was an important thing to explain before he left the world.