Jesus is saying that He is the one true light which no one can extinguish. The light Jesus came to give is the light of God’s revelation. This light of God exposes the darkness of sin that is in our lives. Which is sometimes hidden and unknown to us. God’s light brings healing and freedom.
Have mercy on me, O God, for people assail me; they fight me all day long and oppress me. Cf. Ps 55.2