$ cat t.pl
#/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

my @a = (1, 2, 3);

print "Size of a: ", scalar(@a), "\n";
print Dumper(\@a),"\n";

my @b = [0, 1, 2];
print "Size of b: ", scalar(@b), "\n";
print Dumper(\@b),"\n";

print "Size of b[0]: ", scalar(@{$b[0]}), "\n";
print Dumper($b[0]),"\n";