*他是谁？

Ta shi shei?
他 means he
谁 means who
Pronounced like “top shit shay”

Pretty straightforward, use this question if you want to know who someone is.

他是谁？
他是王明。
Ta shi shei?
Ta shi Wangming.
Who is he?
He’s Wangming.

*他 is a very interesting word in Chinese. It’s interesting in that the female equivalent, 她 she is pronounced the very same way. The gender neutral 它, it is also pronounced the same way as 她 and 他.