Short answers, pulled from the story.
Nut is the ancient Egyptian goddess of the sky who appears as a nude woman arching over the earth with stars speckling her skin. She emerges in the Heliopolitan creation story as the daughter of Shu and Tefnut and mates with Geb to produce Osiris Set Isis and Nephthys.
The name Nut appears in hieroglyphs as a symbol for sky though ancient Egyptian vowels remain uncertain to modern ears. Scholars transcribe her name as Nut Nunut Nenet Nuit or Not depending on the source text and she often wears a water-pot hieroglyph above her head.
An ancient collection called The Fundamentals of the Course of the Stars known as the Book of Nut dates back at least to 2,000 BC making it one of the earliest such records. This astronomical text plays the primary role in guiding the cycles of stars and planets within its pages.
Ancient Egyptians believed the sun traveled across Nut's body during daylight hours before being swallowed by her form at dusk to pass through her belly. Dawn brought rebirth as the sun emerged from her again each morning while she protected Ra the sun god by enveloping him within her star-filled body.
The Greek philosopher Plutarch wrote De Iside et Osiride during the first century CE and likely equated Rhea with the Egyptian goddess Nut based on available information. He described how she gave birth to five children on each of five extra intercalary days though E. A. Wallis Budge argued Plutarch incorporated imaginative embellishments or misinformation into his description.