German is the official language of Bern and Biel-Bienne is bilingual French and German. French and German language courses are widely available. The Integration-BE platform (DE) provides a comprehensive list of language courses in Canton Bern (DE), focusing strongly on integration. Some well-known language schools in the area include Migro Klubschule, Berlitz (in Bern and Biel-Bienne), Inlingua, Flying Teachers and Alemania. Volkschochschule (DE) Bern offers German courses as well as courses for 14 other languages.
If you prefer to practise outside of the traditional classroom setting, you might try Toastmasters or Rhetorik Club Bern (DE) to meet new people and practice your language skills. "Mukideutsch" (DE) is a language course for parents and children together. German courses are offered for free to students at the University of Bern.