For example, a person can say that he prefers a green background when he is using one app and another app can pick up that preference and set the background of the second app green. This feature lets multiple apps or multiple people access the same data stored in the cloud. This is a very powerful feature. Data is stored in the Google cloud.
This is very straight forward to do in Google App Inventor. I created an app where the user choose the background color for the app. The app stores the data in the Google cloud. When the user restarts the app, it retrieves the data from the cloud and uses that information to set the background color.
Here is a video demonstrating the concept using two mobile apps.
Here is the complete code for the mobile application, i built to explore this feature.