Exploring filter can be opened with the menu (arrow) button in the Tools panel right next to the exploring icon 

With the Exploring Filter you can select which types of nodes (based on their labels) and which types of relationships are added to the visualization when you are using the exploring functionality in Graphlytic. Preselect the configuration and explore parts of the graph or control the filtering before adding any new elements to the visualization. 

This can be helpful when your graph model has nodes with high degree which can lead to cluttered visualizations very quickly. Filtering can be also used for exploring only some layers of the graph model.

Please read the help info window in the screenshot for more information on how to use the Exploring Filter.