To put your functions and package global variables into their own package/module, just create a Foobar.pm file (in the same dir as your script) and put your subs in it like so:

package Foobar;

use strict;
use warnings;

our $some_global_var = 8;

sub some_sub {
    print "Hi from Foobar::some_sub().\n";
}

1;
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Now, in your script, to use that new module you just created:

#!/usr/bin/env perl

use strict;
use warnings;

use lib '.';
use Foobar;

Foobar::some_sub();

print "The global var is $Foobar::some_global_var.\n";
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That's it.