This is the 635th most frequent Korean word.
반
"반" means "half" or "class" depending on context.
Here, 반 is used to mean 'half' of something, representing a portion or part.
책의 반을 읽었어요.
I read half of the book.
In this context, 반 refers to a 'classroom' or a 'class group' in an educational setting.
수업 후에 우리는 반에 돌아갔어요.
After class, we returned to the classroom.
Here, 반 is part of the word 반하다, meaning 'to fall for' or 'to be attracted to' someone.