In our Galaxy, the Milky Way, there are 7.5 million human civilizations at different levels of evolution. The extraterrestrial human beings that Billy met are from different places like the Plejaren star system, from the Vega, Lyra, Deneb star systems and also the DAL Universe. The DAL Universe is a parallel Universe to ours, which is called the DERN Universe by the Plejaren. The Plejaren come from a system that is 80 light years beyond the Pleiades star cluster, shifted one fraction of a second in another dimension.
Billy's main contact ETs humans: