Hola Cindy!
I agree with the above expert's answer and suppose too that you meant when to use 'antes de' or 'antes que'
It is correct, you use 'antes de' with time. (Example: Regreso antes de las cinco./I will be back before 5.)
Or can be used before a verb: El se lava las manos antes de comer./He washes his hands before eating.
And 'antes que' goes usually before a noun or pronoun (Ex.: Yo llegaré antes que ella./I will arrive before her)
It can also be used in the subjunctive mood: El quiere comer antes que sirvas el café./He wants to eat before you serve coffee.)