Paypal and most other sites with logins utilize a secured connection of their own and, when properly configured, will encrypt all communication between your browser and their server on their own.
VPNs are protected tunnels connecting computers. If a computer in the VPN connects to a secured site, the security of the site will run IN ADDITION TO the protection of the tunnel.
If you are connecting to an unsecured site or an improperly secured site, the VPN administrators may be able to see the data passed between your computer and the target server.
Your paypal password is actually never sent to the VPN server but rather it is a hash of your password that is sent. However, it is not entire immune to man-in-the-middle attacks, see the answer below. – some user – 2015-06-22T20:14:25.530
https connection is secure. The only way a VPN service could intercept it is if you were connecting to a secure website through a MiTM attack. – Ramhound – 2015-06-22T20:21:26.300