。
I really love rocks, you know.
Literal
I [topic-は] rocks [subject-が] greatly-like [explanatory-なんだ] [insistence-よ] [agreement-ね].
大好き is the emphatic form of 好き, built by prefixing 大. The なんだ ending (colloquial のだ) adds a confiding nuance — 'the thing is, I love rocks.' よね combines assertion (よ) with seeking confirmation (ね), a very common conversational softener.