Question

Как будет по английски: кто это?

Answer 1

Who is it?
кто это, кто это, кто это

Answer 2

Who is he?
Who is she?

Answer 3

"How do you say 'who is this?' in English?"

The phrase "who is this?" is already in English. It is used to ask for the identity of a person you are speaking to or referring to. It is a common question when you receive a phone call from an unknown number or when someone approaches you and you don't recognize them.