In the college students' leave slip, it means: I didn't go through the formal formalities before taking leave, and I came back after the holiday to go through the formalities.
This process is to prove that you have finished your vacation on time and returned to school. The procedure of terminating leave generally corresponds to the procedure of asking for leave. For example, I didn't go through the formal leave formalities before the start of the holiday, and I need to go through the leave cancellation formalities when I return to school after the holiday.