Like WordPress, BuddyPress has the built in capability to be used in any language. To the right is a list of all currently availiable BuddyPress language translation files.
How to use the language file
Put it in the “bp-languages” folder in the BuddyPress plugin folder, and make sure you have enabled the same language in your WPMU settings.
Is your language missing?
If you do not see your language in the list, please consider creating a translation file. For instructions, please take a look at Translating WordPress as many of the instructions there can be applied to BuddyPress.
You can find the latest BuddyPress PO file here: http://svn.buddypress.org/trunk/bp-languages/buddypress.pot or in /bp-languages/ in a BuddyPress trunk check out.