Very Easy
Admin Panel > Categories > Subcategory ( click which one if you want ) click " edit " and translate it into your language,
Note 1: You need to also select " Language name " top " of categories , on right side...
Note 2 : If your language package in OSCLASS market, load it, it will be translated automatically
Note 3 : If you add manually category / subcategory, than you translate manually as I explained above
See secreenshoot,
I gave my web site example...