This is the 22nd most frequent Korean word.
뒤
"뒤" means "back" or "behind" in English.
In this sentence, '뒤' means 'behind' or 'at the back of', indicating a position relative to another object (the door).
그는 문 뒤에 숨어 있었습니다.
He was hiding behind the door.
Here, '뒤' signifies 'after', describing a sequence in time following the end of the class.
수업이 끝난 뒤에 우리는 점심을 먹으러 갔어요.
After the class ended, we went to have lunch.
In this context, '뒤에서' means 'from behind', often implying an indirect or subtle way of doing something.