In this situation, why do you have to wait before the left turn?

In this scenario, you must wait before turning left because the motorbike coming from the opposite direction has the right of way. When making a left turn at an intersection, German traffic rules require you to yield to all oncoming vehicles driving straight or turning right—including motorcycles—regardless of your own priority. The red car and bicycle do not have priority over you in this situation, so only the motorbike is relevant. Always remember: before turning left, look out for oncoming traffic and yield to them to avoid accidents and meet the legal requirement.