What is a Module Manager In Build Settings?

I have unity 5.3.2 and when I go to build settings than click on iOS, Android etc. I see a button labeled Module Manager [http://postimg.org/image/4l56rurxn/]. So how do I publish my app to the play/app stores?

If you need more modules, run the installer again, deselect all and select the modules you need. They’ve split up Unity so there’s no need for installing everything if not needed.
for that window, I find it rather useless, but maybe there is or will be some more functionality to it