To prepare yourself linguistically, you can use various options.

You can take semester language courses at the Language Center of Freie Universität and learn languages independently or in tandem at the Self-Study Center.

If you would like to take a language course abroad, you can apply for PROMOS language course funding.

Possibly the host university offers language courses before the beginning of the semester abroad and during the semester.

Furthermore, other Berlin universities offer language courses, such as the TU Berlin with the Language and Culture Exchange.