From a 2D circuit board, you can create a 3D board by clicking Switch > Push to 3D PCB. In the 3D PCB toolbar, you can move components, flip them to the opposite side of the board, add holes in the board, and push changes to the 2D board, to keep both documents synchronized.
If the 3D board was created independently, a tool is provided to link the 3D design to a 2D PCB, if a suitable design exists.