Openvpn for Android is an open source client based on the open source OpenVPN project.
It uses the VPNService API of Android 4.0+ and requires neither Jailbreak nor root on your telephone.

FAQ

Can I get free Internet
No, this app is for connecting to an OpenVPN server.

How to connect
OpenVPN is a client software to connect to an OpenVPN server. It is not an APP selling or provding any VPN services.
It allows to your own/company/university/provider OpenVPN server or to the VPN service of many