... your number one stop.
Languages are handled by "locale" ... google "linux locale".
Keymaps are utf8 (Like ansi only much bigger)
Fonts can be in a variety of types. eg. MS TTF fonts are supported. Also postscript and bitmap. So these are keywords for googling too.
Language varies only in the number of locales pre-installed. You can always install more or make your own. The whole subject is too big for here so you need lots of reading. Have fun.