These apply to all platforms PC, Xbox One and PlayStation 4.
I have created a listing of which countries carry which languages.
Usually because they are interested in ordering a copy from a 'foreign' (a country outside where they live) country or they live in a 'foreign' (a country they are not from) country and want to get a copy with their native language. I have seen people asking questions about which languages come with which versions of the game. The Witcher 3: Wild Hunt Language availability