What must you be prepared for here?

Your answer was fully correct.

Here’s why all three points apply:

1. People walking on the road: The sign indicates a parking area often used by pedestrians, such as a school or playground zone, so you must expect pedestrians crossing or walking near the road.
2. Oncoming vehicles turning left: Because the road curves and parking spaces are nearby, oncoming traffic might make left turns across your lane.
3. Vehicles turning onto the road: Vehicles parked or stopped might enter back onto the road, so you must be prepared for vehicles merging into your lane.

In German traffic rules, when you see signs indicating pedestrian areas or parking near the road, you must drive cautiously and anticipate these hazards. This helps prevent accidents in areas with pedestrians and turning or merging vehicles.