Atum = a creator god, described as having come into existence (or always having existed) on a hill in an ocean, and then brought forth Shu and Tefnut, who in turn brought forth Nut and Geb, who in turn brought forth the last four. To the best of my knowledge, there's no mythological precedent for him being a fire/sun god as he's portrayed in SOTM.
Shu = God of the air, plain and simple.
Tefnut = Officially, she was supposed to be the goddess of "moisture". The Egyptians, shamelessly prurient as they were, had several theories about how exactly Atum had produced her. It's probably for the best that SOTM didn't try to be too literal here either.
Geb = God of the earth.
Nuit = Goddess of the night sky. In mythology, Geb and Nuit couldn't stop shagging each other nonstop until someone (Atum I suspect) physically separated them, creating the heavens and the earth.
Osiris = Ruler of the kingdom of the dead (which is NOT the same as being the "god of death" in a culture as death-obsessed as Egypt).
Isis = Goddess of birth and life. In many of the myths, she was described as having gathered up the pieces of her husband Osiris and brought him back to life, after he was killed and dismembered by his brother Set.
Nephthys = Goddess of the process of dying (which, again, is not entirely the same as being "goddess of death", though it's closer). Wife of Set.
Set = God of storms and war. Generally something of the bad guy in Egyptian myth, similar to Loki in the Norse canon (there were nastier creatures, all-destroying monsters such as Apepi and Fafnir, but Set and Loki were members of the pantheon who should have known better, and were into stirring up trouble just for the sake of doing so - basically they were the Internet trolls of their time, not precisely "evil" but certainly a serious pain in everyone's collective arse).
I'm probably missing a fair number of nuances, but this gives the gist of it.
Whose turn is it to ask a question?