How was there light before the sun was created?

Hi rabbi, G-d created day and night before creating the luminaries. How is this possible?

First, God created the concept of light and darkness, regardless of the luminaries. He has no limitations & is not bound by anything, and accordingly doesn't need a sun to make light. Only afterwards, on the 4th day, He created the sun and the moon, which is the center or source of the light that we are familiar with today.