This command will create a PDF printout of the PCB. The following example prints the front side in front of the back side:
kicad-cli pcb export pdf MyPCB.kicad_pcb -l "F.Cu,F.Mask,F.Silkscreen,F.Courtyard,Edge.Cuts,B.Cu,B.Mask,B.Silkscreen,B.Courtyard" -o MyPCB.front.pdf
This is the corresponding command to print just the back side, so that it isn’t occluded by the front side.
kicad-cli pcb export pdf MyPCB.kicad_pcb -l "B.Cu,B.Mask,B.Silkscreen,B.Courtyard,Edge.Cuts" -o MyPCB.back.pdf