。
She knows a lot about the latest trends.
Literal
She [topic-は] recent [genitive-の] trends [about-について] well knows.
~について ('about, concerning') is the standard frame for the topic of knowledge, opinion, or discussion: ~について話す ('talk about'), ~について考える ('think about'), ~について知る ('know about'). The progressive 知っている is the canonical way to express the state of 'knowing' — Japanese treats knowledge as a state you've entered into, not a single moment of acquiring; the bare 知る would mean 'come to know' rather than 'know.' The negation よく知らない follows the same logic.