In American Sign Language, raising eyebrows has many functions. It can be used to ask yes/no. You can set context when telling a story. With lowered eyebrows you turn a "w" word (who/what/when etc.) into a question.
But also, you use this more then you realize regardless of your language. If you lock eyes with a stranger at a bar then raise eyebrows, it means "you interested?" In regular conversation it means "are you serious?" or "wow!" depending on context. At a party it might be how you ask your friend across the room if they're ready to leave or if they're feeling safe.