That's a single scalar value, which is the anonymous array reference containing a list of references to the individual elements of the array @foo. Maybe this will clear it up.

use Data::Dumper qw( Dumper );
my @foo = qw( a b c );
my $x = [ \( @foo ) ];
print Dumper( $x ), "\n";
${ $x->[1] } = 'z';
print join( "\n", @foo ), "\n";
print Dumper( $x ), "\n";
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