This made more sense to me once I had a look at the array contents. The rank array stores the key names at the index locations corresponding to the values.

use strict;
use warnings;
use Data::Dumper;

my %data = 
(
      'car'        => 10,
      'motorcycle' => 7,
      'skate'      => 7,
      'board'      => 2,
      'roller'      => 4,
      'vase'      => 4,
      'bird'       => 4,
);

my ($n, @rank) = 1;
foreach( keys %data){
    $rank[ $data{$_} ] .= "$_\n" ;
}
print Dumper(\@rank);
defined and $n += print s/^/$n - /gmr for reverse @rank;

__DATA__
$VAR1 = [
          undef,
          undef,
          'board
',
          undef,
          'vase
bird
roller
',
          undef,
          undef,
          'motorcycle
skate
',
          undef,
          undef,
          'car
'
        ];
1 - car
2 - motorcycle
2 - skate
3 - vase
3 - bird
3 - roller
4 - board
[download]