The bundle ID is the unique identifier of your app. Bundle ID is the term used for iOS apps. For Android apps it is called “Package name”.
A bundle ID/Package name is created automatically when you create an app. It is available in your /backoffice in Manage > Applications.
“Unique identifier” means that there isn’t two apps on the stores with the same bundle ID (for the Apple Store) or Package name (for Google Play store).
You can change the beginning of the Bundle ID (xyz.mobileappcms.mae.ios) and the Package name (xyz.mobileappcms.mae.android) for the whole platform in your Backoffice -> General -> “Your Applications” tab:
Note: It won’t change the Package Name/Bundle ID of apps already created.