What
pronoun, interjection, の adjective
The kanji and the word are exactly the same. That means they share meanings as well.
なに
なん
The reading for this word is the same as the reading you learned with the kanji. What? Yeah, that's what.
何と言いますか。
What would you say?
あなた、何さまのつもりですか。
Who do you think you are?
僕達がタイのホテルで飲んだ飲み物の名前は何？
What was the name of that drink we had at the hotel in Thailand?