Short answers, pulled from the story.
The name Adonis comes from a Canaanite word meaning lord. This term connects the Greek god to ancient Near Eastern traditions stretching back centuries before classical Greece formed. Scholars trace this linguistic root to the Hebrew title Adonai, still used in Judaism today.
Greek women planted gardens inside small baskets or broken pottery containing lettuce, fennel, wheat, and barley on rooftops exposed to intense summer heat. Participants climbed ladders to place these gardens upward where plants sprouted rapidly but withered quickly under the sun's glare. Once vegetation died, they mourned loudly by tearing clothes and beating their breasts publicly before throwing the effigy and withered plants into ocean waters.
Adonis was born to Myrrha who transformed into a myrrh tree after being cursed with insatiable lust for her own father King Cinyras. The transformation occurred during a festival honoring Demeter when Myrrha's mother was absent. Ovid describes how the story falls within conventional classical ideas about sex and gender roles.
Zeus decreed that Adonis would spend one third of year with Aphrodite, another third with Persephone, and final third wherever chosen. Adonis selected Aphrodite remaining constantly together according to most versions. Another account states both goddesses kept him half-year each at Muse Calliope suggestion.
Sir James George Frazer wrote extensively about Adonis claiming he exemplified dying-and-rising god archetype found across cultures worldwide. Mid-twentieth century scholars began criticizing this designation arguing deities better termed separately as dying gods and disappearing gods. Gods who died did not return while those returning never truly died according to critics.