Allah, is the supreme God who created everyone and everything, here on earth and everywhere else in the universe.
As for the name “Allah”, it is the proper Arabic name for God. It is unique, with no plural or gender. He created Adam, and Eve, and from them He created all of humanity.
Over time humanity lost its ways of worshipping Allah, so Allah sent different messengers (human beings) to guide humanity back to the right path of knowing and worshiping Allah.
As humans, we cannot give justice when we attempt to describe Allah. The best way we can describe Him is to quote Allah Himself, and how He describes Himself in the Holy Quran. The Arabic (original) version first, then the attempt some scholars made to translate it to English, to bring the meaning closer to you. Here it is: