The usage count column shows how many times a given tag is used in your project. If you hover over the Usage Count cell, the tooltip will show you exactly where the tag is used:

When you want to see exactly where is the tag used you can just simply mark by click on a part where is the tag used and myDESIGNER will take you to the place where is the tag used, or if it’s used on object/component or animation it will mark and select the where is the tag used for you.