The 5 GHz band is a license-free radio range with far more non-overlapping channels and higher throughput than 2.4 GHz. Its shorter wavelength loses energy faster through walls and distance, so a 5 GHz link needs closer access points or a reasonably clear path.
5 GHz is the usual choice when throughput matters and distance is short: dense access point layouts, high-resolution video backhaul and buildings where 2.4 GHz is already saturated.
More channels, less crowding
The band holds many more usable channels, so several access points can run side by side. Some of those channels are shared with weather and airport radar and require the equipment to detect radar and move automatically.
Where range becomes the limit
Higher frequencies attenuate faster through walls, brick and glass. A camera that holds a link on 2.4 GHz at the far end of a yard may drop out on 5 GHz from the same position.