Omelet plate is a special Catalan plate made for turning and serving omelets. Usually, the most common omelet is one that has potatoes and onions as ingredients. In a frying pan, they are cooked until soft and then the beaten eggs are added. When the base of the omelet starts to get solid but the top is still liquid, the omelet plate, held by the leg like a lid, is put on top, pan and plate are held together and turned over. Your omelet is now on the plate, you can eat it as it is or slide it back into the pan to cook it a bit more.
The words on the plate say Tomba Truites which means Turn Omelets in Catalan.