A Scene is a collection of Objects that represent different unique places within your User Interface, such as menus, maps, and media players. Each Scene has its own 3D space. The Size and Resolution of each 3D space are determined by the Attributes of the Screen that it is assigned to.
The Scene Object doesn't have any Attributes of its own, unlike every other Object in Incari.
There are a few Nodes, such as the KeyPress Node, which require a Scene Object to be assigned as an Attribute. This can be done by dragging and dropping a Scene from the Project Outliner into the Scene Attribute of that Node.