What is Sell Limit order?

It is a pending order, which means  to sell when the bid price gets equal to the specified value. Herewith, the current price level is lower than the value of the set order. Typically, the orders of this type are set in reliance on the assumption that the instrument price, having risen to a certain level, will stop its uptrend and start to decline. It is impossible to set sell limit orders below the current bid price, you have to use sell stop orders for this.