Hi, and thank you for your interest!
YunoHost is being translated using Weblate, a web tool designed to ease translating for both developers and translators.
Translation project for YunoHost currently contains 1544 strings for translation and is being translated into 13 languages. Overall, these translations are 52.1% complete.
If you would like to contribute to translation of YunoHost, you need to register on this server.
Once you have activated your account just proceed to the translation section.