"Jego hobby to geografia."

Translation: His hobby is geography.

[Salander_s]

Strange audio.

[Jellei]

A bit. "hobby" should be pronounced more like 'hobbi', and the double b does sound strange indeed.

[wiktorka234]

Does "hobby" ever change form in Polish, or does it stay the same always?

[immery]

the noun stays the same. Adjective is hobbistyczny and acts like all adjectives.

[BartoszKod1]

Geography is his hobby is not acceptable???

[Jellei]

The subject is different. In "Jego hobby to geografia", 'geography' is a new piece of information, not something you knew from the beginning.