with "the numbers" I'm guessing you mean those at the left corner? They are the stats of the current selected gun. So, how much damage they do and how often they can shoot. The letters underneath "Patterns" mean the patterns that your bullets follow. Every line is 1 pattern, and every letter inside a pattern stands for 1 direction the bullet goes into.
So, the pattern FR means that the bullet goes forward and then right. While BL means backwards and left.
Anyway, nice to hear that you liked it :)