It is a state function of a system, an extensive quantity.
Similar expressions are valid for electric charge or any other extensive quantity associated with countable objects.
This is the experimental expression of volume as an extensive quantity.
Internal energy is an extensive quantity: it depends on how much stuff you have.
The mechanics of macroscopic systems depends on a number of extensive quantities.
Thus the extensive quantity of a substance is a first actuality when compared to the shape.
Thus, magnitude does depend on the extent of the entity or system in the case of extensive quantity.
Consequently, it has a quantity, but not an extensive quantity.
In the former case they are extensive quantities; in the latter, intensive.
It is a state function and an extensive quantity.
