What does this traffic sign combination indicate?

Your answer is correct. This traffic sign combination indicates the end of a traffic-calming zone (Spielstraße). In such zones, special rules apply: pedestrians may use the entire street, children are allowed to play, and vehicles must drive at walking speed and yield to pedestrians. When you see this sign with the red diagonal line, it means these rules no longer apply beyond this point, and normal traffic regulations resume. Understanding this helps you recognize areas where extra caution and reduced speed are required to protect vulnerable road users.