The variables declared in Variables.ps1 are at “Script Scope”. That is you can not see them outside of the scope of the script that declares them. One way to bring the variables in Variables.ps1 to the scope of main.ps1 is to “dot source” Variables.ps1. This, in effect, runs Variables.ps1 at the scope of main.ps1. To do this, just stick a period and space before your invocation of the script:
. .\Variables.ps1
$var1
$var2