Question:What is Hubble's Law?
Hubble's law says that the distance to other galaxies is directly proportional to how quickly those galaxies are moving away from the Milky Way.
So a Galaxy that is twice as far away from our Galaxy is moving away twice as quickly; and a Galaxy that is moving away at a third of the speed of another Galaxy will only be a third of the distance away from ours.
Graph of Hubble Law data for some real galaxies.
Video exlpaining Stellar red shift and Hubble's Law as proof of Big Bang theory.