Works the same as Hide products I already own, instead shows me the items I have already purchased while browsing the categories. Shows all items I own with pictures on the page without me having to click the order to see what is part of the order. 

This image shows that I own six of 134 items on this page that are on sale in this category. It shows the six items I own.  Now if I had clicked hide the items I own, it would only shop me the items I do not own. This cuts down my browse time when I am shopping.  Sometimes I just want a fast way to see what I own in a particular category. It is just a matter or a query similar to what is used to Hide products I already own in the store.