IPFire is translated into many languages so that users from all over the world can use it in their native language or one that suites them best. Of course nobody speaks all languages, so we are a group of volunteers who translates IPFire into those languages where each and everyone contributes the languages they are speaking.
We use Pootle to track translations and make editing language files easy.
There are also various mailing lists available to coordinate translation:
Go to https://pootle.ipfire.org/ and create an account if you don't have one already. Select a project and language and start translating. It is as easy as that!
If you want to add a new language, it is important to know that this requires constant translating. It would be great if you find some more people who want to help translating into that language so that you can share the work. If you are ready for that commitment go ahead. Otherwise it is probably better for someone to use IPFire in English instead of a half-done language.