What does the class mean when buying an SDcard?

This explains it.

So it’s basically how fast the device is allowed to write to the the card right? Even if you bought the highest class card, the device would need to be capable of writing the informaiton that quickly correct?

Correct.
I have a cheap Canon point-and-shoot camera. When I first bought it, I put a class 2 card in and started taking photos. The camera took longer than I expected to actually save the photo, so it slowed down my shooting. I replaced it with a higher class card and the speed improvement was significant. I ended up doing some tests with a stop-watch, and it was definitely half the time.

Good to know, glad I asked about it before making a purchase. It’s for my cell phone but I don’t want it writing media to the card slow.

Go for cat 6 at least.