The Asset Map will display all of your assets/devices on a single map as either individual markers or as clusters. When many things are in one area, they will display as a cluster. The number on a cluster indicates how many markers it contains. Notice that as you zoom into any of the cluster locations, the number on the cluster decreases, and you begin to see the individual markers on the map:
When you click on an individual marker it will display the asset/device key, name, and the last timestamp that it reported in at this location.