This is the 478th most frequent Spanish word.
quién
"Quién" means "who" in English.
Here, 'quién' is used as an interrogative pronoun to ask about a person.
¿Quién está en la casa?
Who is in the house?
'Quién' functions as a relative pronoun, referring to an unknown individual.
No sé quién hizo eso.
I don't know who did that.
'Quién' serves as the object of the preposition 'con' in an interrogative sentence.