A VPN is basically an extension of your home network. It bridges the gap between a Local area network and a public worldwide network, it lets users transfer data across networks as if their devices were apart of the host network. Applications can use VPNs for security purposes but also to give different access to information transfer.
VPN stands for Virtual Private network, and it can keep your activity more private. It can also allow you to be able to access your employer's private network while actually outside of the network. It can also allow you to fool websites into thinking you are in one location when in fact you are in another.
A VPN, short for virtual private network, is a network that is constructed using public wires — usually the Internet — to connect to a private network, such as a company's internal network. There are a number of systems that enable you to create networks using the Internet as the medium for transporting data. Just googled it's defination
Just be careful if you use a free VPN or one that isn't trusted. It may have the opposite effect of privacy by allowing them to view and log all the information you browse.