que dejes de fumar

that you stop smoking

→ que
phrase Uncommon #16,755
that you stop smoking Uses the subjunctive form dejes, often after expressions such as más te vale que (“you’d better”) or to express a demand, recommendation, or necessity. The infinitive form dejar de fumar means “to stop smoking.”
SP: Espero que dejes de fumar pronto.
EN: I hope you stop smoking soon.

Te aconsejo que dejes de fumar.

I advise you to quit smoking.

Cualquier médico te dirá que dejes de fumar.

Any doctor will tell you to stop smoking.

Y quiero que dejes de fumar.

And I want you to quit smoking.

— El profesional (Léon) (1994)

Más te vale que dejes de fumar.

You’d better quit smoking.