。
She loves music.
Literal
She [topic-は] music [subject-が] really-like.
A textbook-clean polite statement: noun + が + 大好き + です. As with all liking expressions, the thing liked takes が, since 好き is grammatically an adjectival noun and the liked object is its subject. 大好き shifts the strength of preference from neutral 好き into strong 'love.'