I prefer vocal music to instrumental music.

Literal

I [topic-は] instruments [than-よりも] vocal-music [direction-のほう] [subject-が] liked.

~よりも~のほうが好きだ ('prefer Y to X') — the standard preference comparison pattern. 楽器 ('musical instruments'). 声楽 (せいがく, 'vocal music'). よりも is an emphatic variant of より.