This is the 1100th most frequent Korean word.
결정할
"결정할" means "to decide" or "to determine."
In this sentence, '결정할' is the future form of '결정하다', meaning 'to decide'. It describes the act of making a decision in the future concerning the selection of clothing.
나는 내일 어떤 옷을 입을지 결정할 것이다.
I will decide what clothes to wear tomorrow.
Here, '결정할' functions to denote a decision that must be made, carrying a sense of responsibility for the process in regard to the progression of an important project.
그는 중요한 프로젝트를 어떻게 진행할지 결정할 책임이 있습니다.
He is responsible for deciding how to proceed with an important project.
In this instance, '결정할' expresses an immediate need to make a decision about something specific, namely the travel schedule.