This is a Pro-Only Feature: you can open the Animancer Tools window to see how it works with Animancer Lite, but it will not actually produce any output unless you purchase Animancer Pro.
Unlike the other Tools, this one is more useful for 3D bone-based animations rather than 2D Sprite-based ones.
Animations store the names of each of the objects in the Hierarchy that they animate so that they can figure out what to control when they are played, but if an object is renamed then the animation will no longer have the correct name so it won't control that object anymore. This Tool allows you to change the object names used by an animation.
If the animation controls lots of different objects, you can use the Copy All button to copy the entire list to the system clipboard so that you can paste it into your text editor of choice, edit it there, then copy the edited list and use the Paste All button to give it back to this tool.