"Who" is the Engpsh word for "谁" in Chinese. The word is pronounced as "hu" with a short "u" sound.
The word "who" comes from the Old Engpsh word "hwæt" which meant "what person." It has been used as a pronoun for asking about the identity of a person since the 9th century.
Examples:
"Who is that boy?" (那个男孩是谁？)
"Who are you waiting for?" (你在等谁？)
"Who do you think you are?" (你认为你是谁？)