my @unholy_mix_of_scalars_and_arrayrefs = (
    'BLACK', [ qw( blue green red yellow ) ],
    'FOO',   [ qw( bar  baz   qux kibble ) ],
);

for my $scalar_or_ref ( @unholy_mix_of_scalars_and_arrayrefs ) {
    my $type = ref $scalar_or_ref;
    if ( not defined $type) {
        print "undef!\n";
    }
    elsif ( $type eq '' ) {
        print "scalar  : $scalar_or_ref\n";
    }
    elsif ( $type eq 'ARRAY' ) {
        print "arrayref: @$scalar_or_ref\n";
    }
    else {
        print "unhandled reftype '$type': $scalar_or_ref\n";
    }
}

# Maybe you meant this instead?
my %sane_hash = (
    'BLACK' => [ qw( blue green red yellow ) ],
    'FOO'   => [ qw( bar  baz   qux kibble ) ],
);
for my $key ( sort keys %sane_hash ) {
    print "key $key, array: @{$sane_hash{$key}}\n";
}
[download]

scalar  : BLACK
arrayref: blue green red yellow
scalar  : FOO
arrayref: bar baz qux kibble
key BLACK, array: blue green red yellow
key FOO, array: bar baz qux kibble

#!/usr/bin/perl

#How can I dereference and print this one:

my @my_array_reference2 = (
    'BLACK', [qw(blue green red yellow)]
);

foreach (@my_array_reference2) {

  if (ref $_ eq 'ARRAY'){print "@$_"}
                         else {print "$_\n"}
};
[download]