This is a simple Intent that can be used to easily open any sound file, from any app.
When an application has to open an audio sound file (like when a file browser need to open an MP3 file or when an Email client needs to open a WAV file in attachment of a received Email), you have the option to open it with this app.
Contrary to other audio players, this player does not use Android media library. So it does not fail to open when the file is not in the Android media library.
In other words, it is just: Open the file, play it and close (with a KISS philosophy).