This services include some useful service that would make your application more powerfull in some way. Now you can refer: + Speech recognition: Use google voice to get voice input then set text output. + Audio manager: Control your phone audio, example set your audio to max, min or ringer mode. + Push notification: Use OneSignal and Google FireBase to manualy or automatically push your notify to devices that installed your application. + Geolocation: Get your latitude, longitude then show your addresses.
Just refer my code, copy may throw some errors that you maybe don't know how to fix! Install plugin before use them, google the keyword for more infomation.