This subroutine returns a hash reference (pointer to a hash.) Curly braces used in this fashion construct an anonymous hash and return a reference to it.
Assuming you call the subroutine something like this:
my $results = _relation();
You would access the elements using the -> dereferencing operator:
$results->{player1} # 0
$results->{player2} # 1
If you want to copy the anonymous hash into a named one, you can dereference the entire thing at once with
my %regular_hash = %$results;
See the Perl References Tutorial for more.