It looks like it inserts components from data(length, width, etc.) that you specify...similar to a dynamic component. Looks useful!
From your link...
@unknownuser said:
How to use the Engineering ToolBox
After loading Sketchup and the Engineering ToolBox from the menu - navigate to the wanted component in the navigation menu above - and select "insert" to add the wanted component to your SketchUp model.
Note! The SketchUp Engineering Toolbox is an online resource updated continuously. You need an internet connection to operate.
For some components parameters like length, color, offset and more can be modified before insertion.
Customized components can be inserted by changing parameters in the dialog boxes at the end of the component lists - and clicking "custom!"
Selected objects in the model can be manipulated - rotated, moved, colors changed and more - from the Tools section.
Assistant objects like lines, horizontal and vertical planes can be added.