IFC files have a tree of products formed by either decompose or containment relations. The viewer product and shape tree shows as much of this structure as it can.

Top-level IFC Projects are shown first, with any contained products appearing as a subtree of components. Each product is tagged with a general description of its type, like WALL, BEAM, or BUILDING. If you are interested in the underlying IFC instances in the IFC file, tooltips on the tree will give you the IDs of the important objects.