The key light brings out the light and darkness of the portrait. Also it brings out the triangle that’s in the models face. Fill light makes the persons face lighter. The background light makes the person to not look like it’s close to the background.
The short light makes the face of the person more softer and calmer. The broad light in the left makes the left side of his face more fierce, and mysterious. The background light gives a high contrast. Also it makes the person seem far from the background.