Final answer:
Harry remembers a blinding flash of green light from the night of his parents' death, signifying the Avada Kedavra curse from Voldemort that killed them and caused his scar.
Step-by-step explanation:
The only thing that Harry can remember about the night of his parents' death is a blinding flash of green light. This memory is significant as it represents the Avada Kedavra curse that killed his parents, James and Lily Potter, and is also the source of his famous lightning bolt-shaped scar. As the curse cast by Lord Voldemort rebounds upon him while trying to kill infant Harry, it leaves Harry as the sole survivor of that tragic night. The green light, therefore, symbolizes the loss of his parents and the beginning of his life as the 'Boy Who Lived.' This minimal memory also speaks to the trauma experienced by Harry, causing a near-total blackout of the event which had a massive impact on his life, shaping his future and his identity.