Each fitting consists of a threaded 3" (approx) nipple piece which passes through a hole drilled in the bulkhead. There's an NPT-threaded hex bushing threaded onto each side to fix the nipple in place. See West marine part number 308213. Or you could use female NPT-to-hose barb adaptors on each side of the nipple --- see WestMarine #3684164. Or you could use a threaded lock nut (see WM #356410, WM has it only in brass, but I can find them in nylon)
Assemble it with a sealant around the wood hole, and appropriate goop on the threads for whatever you're putting in the hoses. On my boat, the hoses carry bilge water, which could have gas or oil in it. So I chose a thread goop appropriate to resist petroleum. I probably used Sikaflex 291 LOT to seal the fittings into the bulkhead. It's resistant enough to gas and oil for occassional, transitory exposure.
Use appropriately rated hose for the application, and SS clamps to attach the hoses.