Assuming you are asking if a kayak cockpit cover is necessary, the answer is maybe. It depends on how and where you paddle.
If you paddle in calm waters close to shore, a cockpit cover isn't necessary. However, if you plan to paddle in rougher water or farther from shore, a cockpit cover can help keep water out of your kayak in the event of a capsize. Cockpit covers also offer some protection from the sun and rain.
Some kayakers use spray skirts instead of cockpit covers. Spray skirts fit snugly around the paddler and the rim of the cockpita to create a barrier against water entering the boat. They are essential gear for whitewater paddling but can be used in other situations as well.
Whether you choose a cockpit cover or spray skirt (or both), be sure to get one that fits your kayak and your paddling style