What Ships in the Box
The 112740-14: That nut and washer are the front-side bulkhead hardware — you need them for the panel mount, and they are included rather than sourced separately.
This jack mounts to a bulkhead from the front side (the nut threads on from behind the panel). The centre contact and shield both terminate by solder — the shield is soldered to the board edge or to a ground plane, and the centre pin is soldered to the signal trace or cable centre conductor. The board edge, end launch mounting style is common for edge-mounted RF jacks where the signal path stays short to the PCB.