Map is a feature that allow you to see your current location on a set of maps that include Streets or Satellite imagery.
You can access the map by tapping on the following icon on the home screen:
The Streets map contains the names of many streets, transport links and places, and so helps you navigate around your immediate vicinity.
The Satellite map contains imagery that might be useful in regions where there aren't any streets to navigate by.
Currently the Map feature requires an internet connection, so if you do not have an internet connection then the Map screen may appear empty.