Hi,
Ok. Let's take it step by step and see if we cannot find a better way of explaining.
Take a look at the first picture in the blog post. Entering GTSpo shows results both for Classes and for Packages. These "Classes" and "Packages" are what we call search categories, and they have associated a query processor that can populate them with results (see the "Spotting your objects" section from the bottom of the post).
In our case, we get 39 classes (of which only 5 are shown) and 1 package that match the query. If you want to look at all those 39 classes, you can dive in the whole collection behind the category in a separate step. This is achieved through Cmd+Shift+ArrowRight. Does it make more sense now?
I did not consider the category to be confusing. Would you propose another name?
Cheers,
Doru