@saxnot
Uh, yes sorry
I still did not write a full explanation on the website...
This tool gives you the total number of toots in your home timeline and the amount of toots in your home timeline by the person you received most toots from

Thus the Gustavino is one of the users you are following; the one you received most toots from.
The name is stupid and could be more explicative: i called it Gustavino because that is the user I receive most toots from.