VPN is Virtual Private Network there. With WiFi and other forms of wireless you are wide open. The VPN is a way to maintain some type of security where none is present like seen in internet cafes.
Wireless can be flaky like when a cab driver goes by and gets on the horn seeing you bumped offline. Complaints are heard about walking out of a room where the wireless router is and seeing the connection strength slip away. Verizon techs note the problems seen with wireless as well over hardwired setups.
When compared to... or over.... hardwired setups referring to the comparison being made between the two. The claims on corded dsl boast faster speeds then delivered. FIOS or Fiber Optics system does far more to deliver there.
The whole concept of VPN technology is to secure a wireless network while connected to unsure ones there. Often these will use a form of encrption while in a public domain.
