The NavTileAgent's area settings.
The area settings dropdown contains two settings related to the agent's interaction with areas.
The first setting is a Unity Event, which fires when the agent moves from one area type to another. When the event is fired, it provides the integer index of the area the agent is transitioning to.
The second setting contains an overview of the area types the agent can walk across. These are determined by the "Walkable Areas" field near the top of the inspector. The areas are displayed with a checkbox and float field next to them. If an area's checkbox is unchecked, the agent uses its default speed when traversing tiles of that area type. If the checkbox is checked, the value provided in the float field is used instead. These speed values translate to Unity units per second.
In the image above, the agent will use its default speed of 3 when traversing tiles with the area type "Walkable", whereas tiles with the "Path" area type will be traversed at a speed of 6, and tiles with the "Sidewalk" area type will be traversed at a speed of 12.