I assume you're referencing green script tiles.
Here's an explanation:
I've squared in the two important parts. Var number is the variable that this script is assigned to. You have to assign each script tile to a variable or it won't work. Var value is the hex value assigned to that script (0x0, 0x1, 0xA, etc.). In order for the script to work, the hex value assigned to the variable at the time the player steps on the tile has to be less than or equal to the value in the Var value box. When the number is greater than the value in the Var value box, the script won't run again.