The sign "Ban on trailer vehicles" indicates that vehicles with trailers are prohibited from proceeding on the road where the sign is posted. This rule is typically enforced in certain areas due to safety concerns, road infrastructure limitations, or to manage traffic flow. It is important for drivers to follow this sign to avoid fines, accidents, and potential traffic disruptions.

Make sure to always look out for additional signs that can provide more context, such as specific times when the ban applies or any alternative routes for trailer vehicles. If you have any more questions about this sign or other traffic rules, feel free to ask!