There are a few issues in your code, as pointed out above you can only return from a subroutine once so the second return is meaningless.

However if you return two arrays they are "flattened" and become indistinguishable. Take a look at the return documentation

As a result you should return references to the two arrays (or other data structure)

I have provided you with a code sample with comments which should make things clearer, play about with it and feel free to ask if you don't follow what it is doing.

use strict;
use warnings;


my @list =qw (1 2 3 4 5);
# define a hash to take back the values
my  %returned_values;
# get the array references
my ($keys, $values) = apackage::ahash(@list);
# Put them in a hash
@returned_values{@{$keys}} = @{$values};
# print out
for my $key (@{$keys}){
    print "$key maps to $returned_values{$key} \n";
}

package apackage;
sub ahash{
    my %hash;
# You are calling the subroutine with an uneven number of elements,
# You should check for this and correct before assigning to a hash
    if ((@_ % 2) != 0){
        push (@_,"null");
    }
    %hash = @_ ;
# Your foreach loop made no sense here
    my @ke = keys %hash;
    my @val = values %hash;
# return references to your two arrays
    return (\@ke, \@val);
# in this context returning a hash makes more sense
}
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