This App is intended to show you the max. number of frames per second that your device is able to process using OpenGL ES.
Not more, not less...
Some Android devices come with some sort of frames-per-second (FPS) cap.
That means that the FPS count is limited to a certain number. Mostly this has something to do with the display that is build into the device.
Most of them are able to refresh at a rate of 60 FPS but some of them are only able to do less FPS rates.