Yeah the mumbers reflect bevels. Bevel numbers are shown here
The first number reflects where the index knuckle should be, and that'll probably be enough to get you going. The second is harder to explain without an actual picture. But it translates roughly to how much of the rest of your hand is on that bevel.
The articles are at tennisplayer and for pay. Worth it BTW. Even if you don't play, those article help you appreciate the pro game so much more.