Jesus continues to teach the crowds. Jesus did not intend for everyone in the crowd to understand this teaching. Therefore, it might be best to simply translate the images, rather than explaining them.
This has several figures of speech. The eye is a metonym for vision, which is a metaphor for understanding. The body is a synecdoche for a person's life. It can be translated as "Your eye is the lamp of your life" or "Your vision is the lamp of your life." Since Jesus was saying something that is true of everyone, it can be translated as "The eye is the lamp of a person's body." (See: [[rc://en/ta/man/translate/figs-metonymy]], [[rc://en/ta/man/translate/figs-metaphor]], [[rc://en/ta/man/translate/figs-synecdoche]])
Light is a metaphor for truth. This metaphor means "your whole life is filled with the light of truth" or "his whole life is filled with truth."(See: [[rc://en/ta/man/translate/figs-metaphor]])
Darkness is a metaphor for falsehood. This metaphor means "When your vision is bad, your whole life is full of falsehood." (See: [[rc://en/ta/man/translate/figs-metaphor]])