The Unreal Engine navigation system utilises a Nav Mesh (Navigation Mesh) to know where the walkable sections of our level are. This allows AI to do pathfinding.

A Navmesh is used by unreal so the AI can pathfind 3D or 2D enviroments. It is generated by a Nav Mesh Bounds Volume, and it's used by the AI system to locate navigable points and move the AI Pawns.

Nav Mesh Bounds Volume can be used to generate several Navmeshes with the purpose of having different pathfinding configurations for different Pawns.