The first step to publish the app is to install Android SDK. First we need to download the Android Studio feom the following link :
1. Install the Android studio. (size ~500 mb)
2. Install the Android SDK tools. (size ~ 2 gb)
-> Make sure latest Java SDK is installed.
-> Make sure Gradle tool is installed ( https://gradle.org/install/ )
-> Accept License agreements in Android Studio. (link)
Once installed you can open your ionic project in the Android studio. This step is optional but gives you access to Android Emulator using which you can test your app in various Android environments.