Translation:German is an important language.
Béarla is indeed the only masculine one. For a good reason: it is not a language as such, named after a country or people. It is a word that originally means 'speech' and is a bit pejoratively refering to English as the lingo of the ruling class... Original full term was Sacs-Bhéarla: Saxon language.
Bunreacht na hÉireann still refers to sacs-Bhéarla:
Éire is ainm don stát nó, sa sacs-Bhéarla, Ireland.
"Is teanga thábhachtach í an Ghearmáinis" - "German is an important language"
"Is teanga thábhachtach í" - "it is an important language"
The "í" refers to "an Ghearmáinis".
Tá gach teanga tábhachtach mar tá gach duine tábhachtach. Is aoibhinn liom Gaeilge!