There are a few types of variables. Most store numbers, but the special reference variables stores pointers to objects in the game world so you can run functions on it later.
Although you can declare a variable to be Short or Long, both produce the same result as Int.
int varNameInt float varNameFloat ref varNameRef
Sizes of numbers that can be stored in each type:
int -2,147,483,648 to 2,147,483,647 float 1.18E-38 to 3.40E38 (single precision = 7 digits) ref an object reference