The Draw Nav Mesh Destination allows an AI's destination to be drawn when within the Scene View. This path is based off of the AI's current destination using Unity's Nav Mesh. This can be helpful to visually see how an AI is navigating around an environment and to ensure an AI's destination is generating correctly. The color of the destination point can also be adjusted.
Important: You will only be able to see the Debugging Tools if Unity's Gizmos Option is on. This is enabled by default (when in Scene View), but if you can't see them, see how to toggle the option with Unity's guide here: https://docs.unity3d.com/Manual/GizmosMenu.html
If you want the Debugger Tools to be enabled while in the Game View, you will need to manually enable the Gizmos Menu.