When Jesus spoke again to the people, he said, “I am the light of the world. Whoever follows me will never walk in darkness, but will have the light of life.”
This is another of the great 'I AM' statements where Jesus is declaring himself to be God. We go right back to the start of the Gospel, "That life was the light of men".
We now know that light is a form of energy. To the Jews, the main source of life was the sun, which gave light, heat and energy. It was the source of life. Not only that, it permits no dark corners, for men love darkness rather than light. With light there is nowhere to hide.
Jesus is claiming to be the source of all life and the dismisser of darkness.