use strict;
use warnings;

my %data = (
    l1 => ['x1', 'x2', 'x3'],
    l2 => ['y1', 'y2', 'y3', 'y4'],
    l3 => ['z1', 'z2', 'z3', 'z4', 'z5'],
);  
my @liste = ();

for my $i (0 .. (keys %data) - 1) {
    my $key = 'l' . ($i+1);
    my $current = $data{$key};
    print "Schleifendurchlauf '$i' ...\n";
    if ($i == 0) {
        @liste = @$current
    }
    else {
        my @list_bak = @liste;
        @liste = ();
        for my $j (0 .. $#$current) {
            push @liste, map {
                "$_-$current->[$j]"
            } @list_bak;
        }
    }
    print Dumper \@liste;
}