So something like

#!/usr/bin/perl

use strict;
use warnings;

my @one = ('vlan 107', 'vlan 121', 'vlan 122,127,129,137');

foreach my $element (@one) {
  my @two = split ',', $element;
  print join "\nvlan ", @two;
  print "\n";
}
[download]

?

This produces:

vlan 107
vlan 121
vlan 122
vlan 127
vlan 129
vlan 137
[download]