foreach my $element (@{$hash{$key}}{
          #work on $element; 
        }

##</code><code>##

use strict;
use warnings;
use Data::Dump qw(pp);


my %hash;
push @{$hash{'article'}},{};
$hash{'article'}[0]= {'SKU'=> ['CDS0013'], 'InternalSKU'=>'179', 'AvailableItems'=>['100']};
$hash{'article'}[1]= {'SKU'=> ['CDS0014'], 'InternalSKU'=>'180', 'AvailableItems'=>['102']};
foreach my $key (keys %hash){
        #print ref $hash{$key},"\n";
        foreach my $element (@{$hash{$key}}){
              #  print ref $element,"\n";
                $articleCount = scalar @{$hash{$key}};   #get the count ...
                foreach my $innerKey(keys %{$element}){
                        print "$element->{$innerKey}","\n";  #some more referencing yet
                        }
                }
        }
print "there are $articleCount articles\n";
print pp \%hash;