Android Release Signing

Before submitting your Android app to Google Play, you'll need to generate a release key and build your app with it.

This process usually goes like this:

  1. Generate release .keystore file using the command line (it's easy, just copy/paste)
  2. Upload your .keystore file to Phonegap Build, add your alias and password
  3. Rebuild your app in Phonegap Build using your release key
  4. Download the signed .apk file, and upload to app store

PhoneGap Build has great documentation on Android signing here.
Another helpful guide when working on Mac can be found 

Signing your Android app keys

Unsigned apps are also known as "debug" versions, and are not accepted in the Google Play Store.