"What does she know?"
Translation:Что она знает?
«Зна́ешь» (znaesh) is the 2nd person form, used with the pronoun «ты» (ty). With the pronoun «она́» (ona) you use the 3rd person form, «зна́ет» (znaet).
This word order emphasises «она». It is used in very few contexts. Usually we can use it when we were talking about someone else before and now I want to talk about 'her'. For example:
— Ты ему́ расска́зывал? 'Did you tell him?'
— Нет. 'No.'
— Хорошо́. А что зна́ет она́? 'OK. And what does she know?'
In this sentence, the last sentence changes whom we're talking about: we were talking about 'him' and now we talk about her 'her', so we emphasise 'her' (by putting it to the end of the sentence) to show this change.
«Что она́ зна́ет», on the other hand, is a neutral word order, and it's useful in much more contexts.
«Какой» is the adjective-like question word, it modifies some noun: «Како́й факт она зна́ет?» (Kakoy fakt ona znaet?) 'What fact does she know?'. When used without a noun, it still implies it.
«Что» (chto, pronounced shto) is a noun-like question word, it is used on its own: «Что она́ зна́ет?» (Chto one znaet?) 'What does she know?'