。
My hobby is listening to music.
Literal
My [genitive-の] hobby [topic-は] music [object-を] listen [nominalizer-こと] [copula-です].
A standard self-introduction sentence. The structure [N1]+は+[clause]+ことです describes what someone's interest, job, or goal is. こと nominalizes the verb phrase 音楽を聞く ('listen to music') so it can serve as a noun complement. A more natural alternative would be 音楽を聞くのが趣味です, using の and switching the topic.