She talks a lot.

Literal

[topic-は] often talks.

しゃべる ('to chat, talk casually') is more colloquial than 話す and connotes informal, often chattery talk — the kind of friend-to-friend conversation you'd have over coffee, distinct from formal speech. With よく as the adverb here, the meaning leans toward 'talks a lot, is talkative' — よく describes both quantity and quality of talking. A short, punchy character sketch.