Processing for Android is two separate things: a programming mode for the Processing Development Environment that allows you to run Processing sketches on Android devices, and the Android version of the Processing core library. The mode uses the core library under the hood so you can write Processing code, but the core library can also be used separately as a regular Java package to include in Android projects developed with Android Studio, IntelliJ IDEA, or any other IDE that supports Android development.
This wiki is concerned with the development of the Processing for Android project, either the mode itself or the core library. For detailed information (installation guide, tutorials, etc.), on how to use the Android mode to write your own sketches, please refer to the official site.