For another way to do it:

use strict;
use warnings;
use Data::Dump qw(dump);

my @arr;

push @arr, [1,2,3];
push @arr, [4,5,6];

print dump (@arr);

prints: ([1, 2, 3], [4, 5, 6])
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It is strongly recommended that you put "use strict; use warnings;" at the start of every bit of code you write. In this case the compiler would have told you "Scalar value @arr1 better written as $arr1" which is a clue that something is wrong, but might not tell you exactly what in this case.

Note also the use of print dump (@arr) to dump the contents of the array. Try this code fragment using "()" in place of the "[]" and see what happens to the contents of the array.