"Ce" means "this/that" as in "this boy " or "this/that month" . You would say "ce garçon" or "ce mois." This is a demonstrative pronoun, pointing out which one you're talking about -- that one.
The "this" or "that" represented by "ça" is more of a standalone "this/that."
I know that : "Je sais ça." I'm using that! "J'utilise ça!"
