use Data::Dumper;
print Dumper($my_ref);
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You showed no effort on your part. What have you tried and found not to work?

sub process {
   my ( $ref ) = @_;

   for my $row ( @$ref ) {
      for my $elem( @$row ) {
         print "'$elem' ";
      }
      print "\n";
   }
}

my @data = ( [ qw( a b c d e) ],
             [ qw( L M N ) ],
             [ qw( 3 1 4 1 5 9 2 6 ) ],
            );

process \@data;
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Perl Best Practices recommends using brackets when conjoining sigils ... @{ $ref } ... which I agree with when the expression is at all complicated. When it is as simple as in this case, however, I think it's straightforward enough -> The data stored in $ref is really an array, so please iterate over the elements.

See also How can I visualize my complex data structure?. You may also try Super Searching for "pretty print" (one hit).