Can you send money western union using PayPal?

Yes, and no. You cannot send money to Western Union from within your PayPal account as Western Union does not accept paypal. This is actually called aggregation which technically may, or may not be legal depending on how the channels are organized because it can easily facilitate money laundering. Aside from that, if you have a paypal debit card then you can send money to Western Union since it acts like an actual credit card.