This is the 1046th most frequent Korean word.
이해할
"To understand" (in its modifying form).
Here, '이해할' is used as a modified form of the verb '이해하다,' indicating the action of understanding something in the future.
그 개념을 이해할 시간이 필요합니다.
I need time to understand the concept.
In this sentence, '이해할' is combined with '수 없다' to express inability to perform the action of understanding.
그가 왜 그렇게 행동했는지 이해할 수 없습니다.
I cannot understand why he acted that way.
'이해할' here indicates the intention or purpose to achieve the understanding, used with '려면' to connect purpose and requirement.