This is the 18390th most frequent Korean word.
승민이가
"승민이가" means "Seungmin (subject marker 'ga')."
In this sentence, '승민이가' is used as the subject of the sentence, marked with the subject particle '이'.
승민이가 친구들에게 선물을 주었다.
Seungmin gave gifts to his friends.
Here, '승민이가' again acts as the subject of the sentence, highlighted with the subject particle '이'.
어제 승민이가 학교에 늦게 갔다.
Yesterday, Seungmin went to school late.
In this sentence, '승민이가' is part of a descriptive clause introducing that Seungmin was the maker of the cake, with '이' marking the subject in the relative clause.