Scope refers to where you are able to access a variable.  Basically variables cannot be accessed from outside the scope they are created in.  Look at the following:

    A = 5

    While A < 10
         B = 1    '-----  B is created inside this loop and cannot be accessed outside of this loop
        A = A + 1  '----- A was created before this loop started so it will be able to be used after this loop ends

    Print B

    The above program WILL NOT COMPILE.  That is because the variable B was created inside the scope of the WHILE loop and nothing outside the WHILE loop will be able to access it.  The variable A was created outside the WHILE loop so the variable A could be used anywhere in this example.  So a variable can go into a deeper scope than where it was created but it cannot go to a lesser scope than where it was created.  A scope deepens every time a new block is started.  Blocks refer to the code within a loop, within a Function, or within a Sub Routine.