NavNesh Areas can affect NavNesh generation and agent behavior/pathing.
The NavMeshArea component is used to define the location, shape and type of an area.

You can also specify the Area for a link component.

The NavMeshAreaDefinition resource is used to define properties of the Area.

Limitations

• Currently there is a limit of 24 NavMeshAreaDefinition, but you can assign them to as many Area Components as you like
• Static areas are basically free.
• Moving areas are a bit more expensive, but you should be able to have at least a couple of dozens of them.