불이 꺼지고

the light goes out and

→ 불
phrase Rare #24,940
the light goes out and 불이 꺼지다 means that a light goes out or turns off. 꺼지고 connects this action to what follows.
KO: 불이 꺼지고 영화가 시작됐어요.
EN: The lights went out, and the movie started.

불이 꺼지고 있어요

The light is going out.

— 길 (1954)