The balloon was a representation of the universe. The dots were galaxies that were moving farther and farther from each other as the balloon/universe expanded. We have 6 difference galaxies represented with letters a-e and m. M is for Milky Way, our home galaxy which was closest to the neck of the balloon.
The Galaxies that were closest to the neck of the balloon moved the least and the ones that started off the farthest from “m” moved further.
The experiment show how the galaxies are expanding and getting bigger