호차 (hocha) means “train car number”

More examples

짐을 몇 호차에 두었는지 기억이 안 나요.chi meul myeot ho cha e tu eon neun ji ki eo gi an na yo

I do not remember which train car I put my luggage in.

The identifying number for a particular car on a train.

칸kan: One individual car or section of a train or subway.
차량charyang: The body of a vehicle or one individual unit of a train.

기차에서 차량을 구분하기 위해 붙이는 번호ki cha e seo cha ryang eul ku bun ha gi wi hae pu chi neun peon ho

The word is built from a number element and a word for car, so it names the number used to identify a train car.

English speakers may confuse this with a seat number, but it identifies the whole car where the seat is located.