This is the 7421st most frequent Korean word.
초등학교에서
"At elementary school."
Here, '초등학교에서' means 'in elementary school,' indicating the location where the activity (playing soccer) took place.
초등학교에서 축구를 했습니다.
I played soccer in elementary school.
In this sentence, '초등학교에서' specifies the context of the subjects being taught in elementary school.
초등학교에서 배우는 과목은 매우 다양합니다.
The subjects taught in elementary school are very diverse.
'초등학교에서' is used here to indicate the setting where the action of making friends occurred.