Meaning of “before” - Learner’s Dictionary

before

conjunction uk us /bɪˈfɔːr/
EARLIER

A2 earlier than the time when something happens:

He was a teacher before he became famous.
It was dark before we found him.
Before I could warn him, he had fallen.
TO AVOID STH

B1 in order to avoid something bad happening:

Put that stick down before you hurt someone.
UNTIL

B1 until:

It took a few moments before I realized that he was lying.

(Definition of “before conjunction” from the Cambridge Learner’s Dictionary © Cambridge University Press)