When you're driving your vehicle at night with your bright headlights on and another vehicle is oncoming with their bright headlights on you need to immediately dim your bright headlights to prevent yourself from being blinded from the oncoming bright headlights.
The oncoming vehicle should dim their bright headlights as well but if they don't then you should dim your headlights anyway and look away from the headlights to prevent yourself from being blinded by other vehicles headlights.