Pages can be folded after printing. (A paper folding unit must be installed on the printer.)
These settings are specified on the [Paper/Imposition/Finishing] screen.
Note that this explanation outlines the finishing settings. For details about a specific setting, see the on-screen balloon help that appears when you click the button.
For details about compatible paper sizes and thicknesses etc., see the documentation of your printer and the paper folding unit.