What must you do upon seeing this traffic sign?

You answered correctly because this sign indicates a pedestrian crossing. According to German traffic rules, you must reduce your speed and approach cautiously, especially if pedestrians appear to want to cross. You are required to give way to pedestrians who have started crossing. Additionally, you must not stop or block the pedestrian crossing, even if traffic behind you is building up, to ensure pedestrians can cross safely and without obstruction. Following these rules helps protect pedestrians and ensures smooth traffic flow.