A certificate means nothing, actually. A prospective client will never ask about your education if you are a styist. If you show your certifiate, it will signal that you are really inexperienced ... so hide it, if you have one. They will ask to see your portfolio, maybe a resume and if that impresses them, they will probably talk to you about the project at hand to see if they like you, your knowlege and ideas and your work ethic. They also will look for stylists who are recommended to them ...probably more than anything ... so reputation is the number one factor in getting gigs.
But ... it's a beginning ... but only that. You are not even close to being prepared to work as a stylist. It takes a couple years minimum, out there testing and building your network and portfolio, before you will probably ever see a dime profit. You should assist for a while and really learn the business from a working pro. Within 6 months after the course, you will understand that they did not really get you started ... only gave you a tiny smattering of information and sent you off in the direction of starting to actually learn the business ... the rest is up to you. You must find a way to begin to build a client list.
And no ... you can't teach styling ... a person has to have the eye for it (for proportion, fit, texture, color, etc.). But they can teach you a bit about how to build your business ... but infortumately most courses only spend a few hours on that. And without that information, and the guts and fortitude to do what it takes, you are probably not going to make it. The business end of it is as or even more important that the "creative" part of it if you expect to actully get paid, eventually.