$ perl -wE'$a = [1,2,3]; say "@${a}";'
1 2 3

##</code><code>##

@$h{a}
=> @{$h}{a}
=> A hash slice that expects $h to be a reference to a hash.

@{ $h{a} }
=> @{$h}{a}
=> An array dereference that expects $h{a} to return an array ref.