This is a contacts app. Primarly used for educational purposes.
This app is used as an example for teaching. It allows people to learn how to do task quicky and learn the principles.
For more information go to John's Android Stuido Tutorials on youtube. https://www.youtube.com/channel/UC8mX-MiAnXtp382gHTQg7Sw/
For more information and documentation of android development go to http://developer.android.com