He asked for the number of elements in the HoA. I took that to mean 5 for the following structure:

my %h = (
   k1 => [ qw( a b c ) ],
   k2 => [ qw( d e ) ],
);
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Your solution simply returns the number of elements in a hash. It could be that's what he meant, but that's now how I interpreted his question.

This is wrong.

Not so hasty on the wrong. Fletch and Jenda also interpreted the question like I did.