What is VPN over VLAN?

Virtual Private Network.. it is used for private communication over public network.

You probably want to say VLAN over VPN, this term used when we want to route our VLAN packets over VPN connection.... moreover it's not possible with IPsec but can be done with GRE tunnel type ..... please check below link may be it's helpful for you....

http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/interface/configuration/xe-3s/ir-xe-3s-book/ir-eogre.html