This command toggles the group member names display, which is used in the Assign Letters Tool.

An object has a Name, which is displayed in the Property Bar when that object is selected. You edit the Name in this field.

With this option checked, that Name will be displayed in the center of each object in a Group.

After you have populated an object, you can use the Assign Letters Tool to give each object a Name. If you have imported text, then this is how you will enter each letter, which will then be used in the Stats.