What must you be prepared for here?

This traffic sign indicates the presence of a "Verkehrshelfer" (traffic assistant), commonly found near schools or crossings where children frequently cross the street. Verkehrshelfer help children cross safely and may temporarily stop traffic. You must be ready to stop if the traffic assistant signals, and you should expect that children will cross more frequently in this area. However, it does not mean that children will be playing on the road under supervision. Always slow down and pay close attention when you see this sign.