Well brother, 12 points means it has 12 possible points of contact with the nut and 6 point is the shape of the nut, a nut has 6 sides thus 6 points of contact.

Having 12 point is nice in a tight area how ever they tend to slip if the nut is damaged. Back in the day I would have told you to buy the 12 point but working on a bike I think 6 point would be better.
You will be fine with Craftsman, don't but that other crap they sell, Champion I think. That stuff is garbage, a complete waste of money.(Imho because of the warranty)

You can start with that set you show and then pick up the wheel wrenches down the road. I think there are only two other sizes that you need for general maintenance.

When you can, get a Craftsman set of Metric 1/4 inch drive sockets. That will make your wrenching world a better place to be!!

Howie