This is the 472nd most frequent Korean word.
이유를
"Reason" (accusative form: "the reason").
Here, '이유를' is used as the object of the verb 'to explain', showing that the 'reason' is what is being explained.
그는 이유를 설명했습니다.
He explained the reason.
In this sentence, '이유를' refers to the personal reason of the subject, used as the object of the action 'to state'.
그녀는 자신의 이유를 말했다.
She stated her reason.
Here, '이유를' is the object of the action 'to search', indicating the motive or justification being sought.