help to understand making process

[Dario Folliero]

Hello: in the image shared by Jeff, he marked the "move selection" option. At the right of it you have a set of four "cuboids":
The first is vertex.
The second is surface.
The tirth is line/conditional line.
The fourth is primitive.
You need to select the last one in order to move the primitive.

You're right, this program makes me feel stupid  I underestimated the last cube. thanks