What does VPN mean on my iPad general page?

Virtual Private Network.

Virtual Private Networks (VPN) are often used within organizations to allow you to communicate private information securely over a public network. You may need to configure VPN, for example, to access your work email on an iOS device. VPN works over both Wi-Fi and cellular data network connections.

Read more about it here.

http://support.apple.com/kb/ht1424

Virtual private network.

It's a way to securely use a public network.