Cornering lights (not to be mistaken with side marker lights) are lights that lid up next to the headlights, when you make a turn. It’s safer for the driver as for the pedestrians because the part where the car turns are lit.
Citroën used the accessoire in a recent print ad of them, where the car lights are being curved, like their logo. And although the lights probably can’t be used like in the ad, it is a nice and simple idea.