An exclamatory expression meaning 'how...!' or 'what...!' used to show surprise or strong feeling.
何てきれいな花なんだろう！
What a beautiful flower!
何てひどいことを言うの！
What a terrible thing to say!
何てことだ！ 財布がない！
Oh no! My wallet is gone!
An interjection meaning 'What?' used to ask someone to repeat or clarify what they said.
A: 明日行けるよ。 B: 何て？もう一度言って。
A: I can go tomorrow. B: What? Say that again.
彼が結婚するって、何て？ 信じられない。
Him getting married—what? I can't believe it.