Or sometimes a cup is just a cup, and two is just representative of two units. Remember that mathematics is merely the method by which we keep track of an object, a concept, a thing. A number which has no purpose or point is just a meaningless unit lost in the infinite cosmos and you can make it anything you want it to be, because the number is attached to nothing.

Meanwhile, back in the real world, if you have two cows, and add two more cows, you have four cows.

The end.