Traffic signs, signboards

Quick answer：

Traffic signs are visual symbols used to communicate information to road users. They include regulatory signs, warning signs, and guide signs. Signboards are structures or displays that hold these signs. In the United States, the Manual on Uniform Traffic Control Devices (MUTCD) governs the design, installation, and use of traffic signs. In Europe, the European Union's Directive 2008/96/EC provides guidelines for traffic sign design and implementation.