I know that Martin Luther knew Latin and German, but did he know other languages? For example, did he know Greek or Hebrew (I mean those Greek and Hebrew that the Bible is written in)?
Luther did translate the bible to what is known as the Luther Bible from old Greek, old Hebrew and Aramaic sources - not the latin translations that were widely used with the catholic church in Germany.
Here are the two hints from the wikipedia article:
He used Erasmus' second edition (1519) of the Greek New Testament, known as the Textus Receptus.
[...] by 1534 he completed his translation of the old and new testaments from Hebrew and Greek into the vernacular [...]
Luther was more familiar with Hebrew
Greek than with Greek Hebrew which is why his translations received help by others - especially Philipp Melanchthon.
Luther must have known at least German, Latin, Greek, Hebrew and Aramaic.