update : taken into account davorg's remarks.

Internally, a hash table can be thought of a sort a "special" list. That means the following hash

%hash = ('test' => '24',
         'blah' => '253');
[download]

can be equivalent to

@hash = ('test', '24', 'blah', '253');
[download]

BTW, => is equivalent to , here.

So if you understand that a hash is a special representation for an list, then you expression does the following :

• Take the array reference corresponding to the hash : %hash
• Derefence it and print it out.

That is, you convert an hash to a array using the references.

HTH