Variables can help you clarify what you code does. Something an obscure data structure does not. For example,

my $DEBUG = 1;

#... later in your code
if ($DEBUG) { warn "Something happened\n" }
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I bet your thinking that this is pretty obvious but I still want to reduce the number of variables.

If you think you have too many variables in a section of code, chances are you have not abstracted out it out enough. Move more of your code into other subroutines to enhance clarity.

my $dimensions = _get_dimensions_for(5,8);

while (my ($r,$s) = each %{ $dimensions } ) {
    print($r);
}
sub _get_dimensions_for { 
  my $x = shift;
  my $y = shift;

  return { 
    x=> $x, 
    y=> $y 
  } 
}
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Note: Thanks to ikegami for pointing out my error.