Commune Veneciarum is a Latin term that means "Commune of Venice." Venice is a city in Italy that is made up of a bunch of smaller parts, kind of like Lego blocks. But instead of being blocks, they are little areas of land called "communes" that make up the whole city.
Commune Veneciarum refers specifically to the group of communes that make up the city of Venice. Think of them as different neighborhoods or sections of the city, where people live, work, and play. By putting all of these communes together, you get Venice as a whole.
In summary, Commune Veneciarum is just a fancy Latin way of talking about the different parts of the city of Venice that come together to create the beautiful place we know and love.