This is the 7342nd most frequent Korean word.
쪽지를
"쪽지를" means "a note" or "a piece of paper" in English.
Here, 쪽지를 (a note) is used as an object of the verb 남기다 (to leave).
학생은 선생님께 쪽지를 남겼어요.
The student left a note for the teacher.
In this example, 쪽지를 is the object of the verb 주고받다 (to exchange).
지난 수업에서 우리가 쪽지를 주고받았어요.
We exchanged notes during the last class.
Here, 쪽지를 refers to a note as a medium for communication and is the object of the verb 사용하다 (to use).