$ cat foo.pl
#!/usr/bin/perl

use strict;
use warnings;
use Getopt::Long;

my %opts;
GetOptions(\%opts, 'foo=s', 'v');
# '=s' modifier means foo needs argument, and it can be
# any string (another modifier is '=i' for integer.)
print "foo = $opts{foo}, verbose = $opts{v}\n";

$ perl foo.pl --foo=bar -v
foo = bar, v = 1
$ ./foo.pl --for=bar -v
foo = bar, v = 1