Spanish phrase
¿Quién sería ~?
Meaning
Who could ___ be?
When to use it
Asks who someone or something could be. Used to speculate politely with low certainty, common when hearing an unexpected sound or call.
Example dialogue
¿Quién sería el que llama a esta hora?
Who could be the one calling at this hour?
Probablemente sea un vecino, no te preocupes.
It's probably a neighbor, don't worry.