Ah ok. I think there should be one variable tutorial somewhere.
Variable is very easy and very very handy thing in all code langauges. It basically stores information.
Most of the variables are integers (stores numbers) and in GEysir (my name for GE code) you can use variables like this:
myvariable = 40; //sets the variable value to 40
anothervariable = myvariable; //sets a variable value to the variable value of another variable
myvariable = 1+1;
myvariable = anothervariable + 1337 + 365;
myvariable += 2; //variable value changes to value + 2 (if it's 1 it becomes 3)
myvariable = xvelocity;
or inside any script that where you can insert numbers.
There is also string variables (store text) but they are level more complicated so you better practise playing with integer variables first.