A limit order is an order type that you place on the order book with a specific limit price. The limit price is determined by you. So when you place a limit order, the trade will only be executed if the market price reaches your limit price. Therefore, you may use limit orders to buy at a lower price or to sell at a higher price than the current market price.
Unlike instant orders, where trades are executed instantly at the current market price, limit orders are placed on the order book and are not executed immediately.