Since nobody else has said it, 'ship parts' is the item name, not referring to any specific parts. It's a general resource for on-the-fly ship repairs.
When you help one of the big two factions in a dog fight that you run across randomly they'll usually hail you and you can ask for ship parts (if they survived). Some vendors have them. Sometimes they drop in wreckage after destroying a ship. They're fairly common when boarding a ship and looting the cargo hold.
The cargo hold is a small screen you can find in the cockpit that you can open like a storage. It's not the captain's locker.
Go to your cockpit. There should be a cargo hold panel there. Buy the ship parts from vendors and put them into your cargo hold via the panel in your cockpit. Then once you've lost hull press O on your keyboard(iunno controller equivalent).