Checking out the demographic distribution of your users will allow you to prioritize and improve specific sections of your app targeted to different audiences. For example, you could move your data and API from EU to Australia if you see that most of your users live there.
Whenever we receive the data from a device, we resolve the GeoLocation (using GeoLite) from the incoming network package based on the IP address and link the device with the location resolved.
You have users in San Francisco, USA, and one of them just opened the app. We will receive a request in our servers from an IP address, from which we'll figure out it's location. The same happens for another user which is in Mumbai, India.
You will be able to see in the world map that USA and India are highlighted countries, adding 1 user per unique device interaction in each for the time period specified.