This is the 9403rd most frequent Korean word.
결성
Formation or establishment.
In this sentence, '결성' refers to the action of forming or establishing a group, in this case, a band.
그들은 이제 공식적으로 밴드를 결성했습니다.
They have officially formed a band now.
Here, '결성' is used to describe the formation of a group or organization dedicated to a specific purpose.
새로운 운동 조직이 결성되어 활동을 시작할 계획입니다.
A new movement organization has been formed and plans to start activities.
This usage of '결성' illustrates the action of creating a temporary or specific subgroup for a particular event or cause.