Figure 1: Tree View
When you click on any view, it will display you all the distinct level 1 fields values (along with their counts). If the number of nodes brought by the query for this first level is greater than the maximum nodes that you defined for this first level field while creating the view, then a new node "See More" will be created in blue color. Clicking on this node will bring the remaining nodes.
Note that it will bring the nodes in chunks of Max Nodes that you defined for this field.
Once you click on any level 1 field, a red light as shown in figure 1 will be displayed along with that node meaning that user has expanded this node. Now if you had defined any level 2 field in the field hierarchy of this view, then all the distinct values of that field would be displayed under the clicked node. Secondly, the Data grid on the right side would also be updated according to new query.