ㄴ가 보다

must be; a guess from evidence

Attaches to a description to mark it as the speaker's conclusion from what is in front of them, not a plain fact: 땀을 너무 흘리시는데... 더우신가 봐 'he's sweating a lot... he must be hot.' The guess is usually about someone else's state or about the situation, and the evidence is visible right there. One line here uses it as a question instead, 아산에서 제일 유명한 장소인가 봐요 여기가?, checking a guess with the listener. Do not confuse it with ㄹ까 보다, which looks similar but means being afraid something will happen.

Register: casual 봐 and polite 봐요 both appear here