Since numerous people have told you already that ->GetActiveWorkflows() returns an arrayref instead of an array, here's the code that does something useful with that:

use TeamSite::WFsystem ;
$system = new TeamSite::WFsystem() ;
my $ar_jobs = $system->GetActiveWorkflows();
foreach my $job (@{$ar_jobs}){
  print "$job \n" ;
}
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Assuming that $job will contain something printable, of course.
@{$ar_jobs} dereferences the arrayreference, which gives you the array that $ar_jobs references to. I usually prefix my arrayref and hashref variables with ar_ and hr_ respectively, so I can easily see what kind of reference I'm dealing with. This is not required, but imo easier to spot.