This is the 736th most frequent Indonesian word.
siapa
"Siapa" means "who" in English.
In this sentence, 'siapa' functions as an interrogative pronoun to ask about the identity of a person.
Siapa yang datang ke pesta tadi malam?
Who came to the party last night?
Here, 'siapa' serves as an embedded question within a larger sentence, still questioning the identity of a person.
Saya tidak tahu siapa yang menelepon saya tadi.
I don't know who called me earlier.
In this example, 'siapa' introduces a relative clause, specifying the subject of an action.