Yap.Town

を理解するのは困難

difficult to understand

→ を
phrase Rare #37,017
difficult to understand A formal-sounding expression meaning that understanding something or someone is difficult. The を marks what is difficult to understand, and のは turns the action into the topic.
JA: この説明を理解するのは困難です。
EN: This explanation is difficult to understand.

彼の言ってる事を理解するのは困難だ。

It's difficult to understand what he's saying.

彼の言っている事を理解するのは困難だった。

It was difficult to understand what he was saying.

彼女が言っていたことを理解するのは困難であった。

It was difficult to understand what she was saying.

私が彼のことを理解するのは困難だ。

I find it difficult to understand him.