In its core, this is just another version of OpenVPN for Android - but with a fresh look, a better handling and additional features such as the build-in display of your public IP address and country.
CentVPN uses Android's VpnService API to function as an OpenVPN client. The app allows users to connect to their own VPN servers using their own configuration files. The developer has no involvement in or access to the VPN servers users connect to — all server configuration is provided entirely by the user.
The VpnService API is used solely to establish the encrypted tunnel between the user's device and their chosen VPN server. All traffic through the tunnel is encrypted end-to-end by the OpenVPN protocol. No user data is transmitted to the app developer.