This is the 11225th most frequent Korean word.
기차가
"기차가" means "train" (subject particle attached).
Subject of the sentence describing the train's action.
기차가 역에 들어오고 있다.
The train is coming into the station.
Subject of the reported speech, focusing on the train's schedule.
기차가 조금 늦는다고 들었어요.
I heard that the train is running a bit late.
Subject of the clause explaining why it is used frequently.