use strict;
use warnings;

my %hash;

$hash{key1} = [ [qw(k1r1f1 k1r1f2 k1r1f3)],
                [qw(k1r2f1 k1r2f2 k1r2f3)],
               ];
$hash{key2} = [ [qw(k2r1f1 k2r1f2 k2r1f3)],
                [qw(k2r2f1 k2r2f2 k2r2f3)],
                [qw(k2r3f1 k2r3f2 k2r3f3)],
               ];

#get the first element of the second row of key1
print $hash{key1}[1][0];

#iterate over the third row in key2
print for (@{$hash{key2}[2]});
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You might want to take a look at the references tutorial