Custom Variables inside Functions

Hello, folks. I'm brand new to this, but I appreciate the help.

I'm trying to figure out how/if i can use a custom variable within a function, and I cant seem to find any real information on it. It appears it may be possible, but the HOW eludes me.

Basically, I have a variable that stores a numerical value for currency. I'm trying to set a function so that when the mod I'm creating calls the procedure, the function will call the variable WITHIN THE COMMAND. Is this possible? Thanks again, in advance.