"Arrêtez" is a French word which means "stop" or "halt." In a restaurant, it can be used to stop or cancel an order. For example, if you have changed your mind about what you want to eat or if you no longer want to order, you can say "Arrêtez, s'il vous plaît" to the waiter or waitress, which translates to "Stop, please." This lets them know that you want to cancel the order.