This is the 11497th most frequent Korean word.
끝나서는
"After finishing" or "once it ends."
Here, '끝나서는' is used to denote the completion of the movie (a temporal marker).
영화가 끝나서는 집에 갔다.
After the movie ended, I went home.
'끝나서는' indicates the conclusion of work, suggesting what action follows.
일이 끝나서는 같이 저녁을 먹자.
After work ends, let’s have dinner together.
In this sentence, '끝나서는' highlights what occurs subsequently to the event's conclusion.