When you build a custom mobile app for the Android or the iOS platform, you can automatically increment the third digit number of the release version by one, as displayed in the Version field, with each build iteration.
In other words, when this option is enabled, automatic increment of version number occurs each time you click Build now or Build again. For instance, when you click this button it increments the version number from '2.3.0' to '2.3.1' .