いけないよ

must not; must

→ いけない

phrase Common #7,666

must not; must Used in expressions such as 〜てはいけないよ (“you must not…”) and 〜なければいけないよ (“you must…”). The よ adds emphasis and makes the statement sound conversational.

JA: ここで写真を撮ってはいけないよ。

EN: You must not take pictures here.

いけないよ

You can't.

— マルコムＸ (1992)

手紙には返事を書かなきゃいけないよ。

You have to write a reply to the letter.

本当にタバコをやめなければいけないよ。

You really have to quit smoking.