彼の行動は

his actions

→ 彼
phrase Rare #23,986
his actions は marks 彼の行動 (his actions) as the topic of the sentence.
JA: 彼の行動は周りの人に大きな影響を与えた。
EN: His actions had a big impact on those around him.

彼の行動は人から非難を受けやすい。

His actions are easily criticized by others.

彼の行動は言葉と一致していなかった。

His actions didn’t match his words.

彼の行動は、父に少しも似ていない。

His behavior is nothing like his father's.

彼の行動は私の最大の関心事だ。

His actions are my greatest concern.

彼の行動は危険だった。

His actions were dangerous.

彼の行動は言葉と必ずしも一致しない。

His actions don't always match his words.

彼の行動は時々奇妙だ。

His behavior is sometimes strange.