What vehicles may enter a zone with this sign?

Your answer is fully correct.

This traffic sign indicates a "bicycle zone," where only bicycles are generally allowed to enter and use the zone. The additional "Anlieger frei" sign means that residents (or those with a legitimate reason, such as property access) are also permitted to enter the zone with their vehicles. Furthermore, small electric vehicles (like e-scooters or electric small cars) that are considered similar to bicycles are also allowed.

So, the rule is:
- Only bicycles, small electric vehicles (like e-scooters), and vehicles driven by residents or those with official reason to enter may use this zone.
- This restriction helps protect the area from through traffic and keeps it safe for cyclists and residents.

Knowing this will help you recognize zones where motor vehicle traffic is restricted except for residents and specific small electric means of transport.