Firstly, you've got to distinguish between lists and arrays. An array is basically a list identified an @-sign.

use strict;
use warnings;

# Assigning a list to an array. @a is now ('a', 'b', 'c').
my @a = ('a', 'b', 'c');

# Assigning an array to a list. $f is 'a'.
my ($f) = @a;

# Assigning a list to a list. $f2 is also 'a'.
my ($f2) = ('a', 'b', 'c');

# Because we're assigning in scalar context,
# the comma operator is used with its scalar
# meaning. In scalar context comma means
# "evaluate the left side, discard that, then
# evaluate the right side". So $l is 'c'.
#
# "use warnings" will give us two errors here
# because 'a' and 'b' are evaluated but never
# used.
my $l = ('a', 'b', 'c');

# Assigning an array to a scalar. $n is 3.
my $n = @a;

use Data::Dumper;
print Dumper {
    '@a'    => \@a,
    '$f'    => $f,
    '$f2'   => $f2,
    '$l'    => $l,
    '$n'    => $n,
    };

__END__

Output is:

$VAR1 = {
          '@a' => [
                    'a',
                    'b',
                    'c'
                  ],
          '$n' => 3,
          '$l' => 'c',
          '$f2' => 'a',
          '$f' => 'a'
        };
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