Numbers 2468, for the four directions in the keypad (ie, the number area), 2 for down, 4 for left, 6 for right, 8 for up
Sometimes there is also a 5, representing no direction
Letters ABCD, for the King of Fighters default kicks, A for light punches, B for light kicks, C for heavy punches, D for heavy kicks
S is short for Start
jbj2c I'm guessing it's Kusanagi's move :Jump Light Kick + Nai Drop