Short answers, pulled from the story.
The Eye of Ra is a divine entity in ancient Egyptian mythology that functions as an extension of the sun god Ra's power. Although equated with the disk of the sun, she frequently acts as an independent goddess, serving as Ra's feminine counterpart, defender, and both mother and daughter in a cycle of solar renewal.
A large number of goddesses were equated with the Eye of Ra, including Hathor, Sekhmet, Bastet, Tefnut, Menhit, Mut, Wadjet, Nekhbet, Renenutet, Weret-hekau, Meretseger, Sothis, Maat, Neith, Isis, and Astarte. Beginning in the Middle Kingdom, the hieroglyph for a uraeus could represent the word "goddess" in any context, because virtually any goddess could be linked to the eye.
In the Destruction of Mankind, recorded in the Book of the Heavenly Cow from the New Kingdom (around 1550-1070 BC), Ra sends the eye in the form of Sekhmet to massacre humans who rebelled against him. Ra stops her by having red-dyed beer poured across the land; she drinks it mistaking it for blood and returns to Ra too intoxicated to finish the slaughter.
In the Distant Goddess myth, the Eye of Ra becomes angry with Ra and flees to a foreign land, sometimes described as Nubia, Libya, or Punt, taking the form of a wild feline. Gods including Anhur, Shu, and Thoth are sent to retrieve her. Her return marks the beginning of the Nile inundation and the new year.
The Pyramid Texts from the Old Kingdom (around 2686-2181 BC) are among the earliest sources for Egyptian mythology and mention both the Eye of Horus and the Eye of Ra. The myth of the eye retrieving Shu and Tefnut is known from allusions in the Coffin Texts of the Middle Kingdom (around 2055-1650 BC) and a fuller account in the Bremner-Rhind Papyrus from the Late Period (664-332 BC).
The Eye of Ra was invoked in temple rituals to defend sacred precincts, with texts specifically calling on sets of four defensive uraei. Magical spells from the New Kingdom directed ordinary people to place clay model uraei around their homes to ward off evil spirits and nightmares. Apotropaic amulets in the shape of the Eye of Horus also invoked the connected power of the Eye of Ra for personal protection.