**Guidance devices** are elements used on roads to **indicate obstacles** that may be encountered along the way. These devices include lights, signs, and other elements that help highlight construction work and guide drivers on the direction they should follow.

- **Beaconing signs** are an example of guidance devices. These signs not only indicate the direction to follow but also alert about obstacles present on the road, such as construction work or temporary closures.

- **Provisional directional panels** and **yellow lights** are examples of devices that help guide drivers and indicate obstacles on the road. These devices are essential for maintaining safety on the roads, especially in construction zones or areas with changing conditions.

Therefore, the main purpose of guidance devices is to **indicate road obstacles**, ensuring that drivers can navigate safely and efficiently.