What is a limit order?
An order to buy or sell at a set price or better; it waits in the order book until the price gets there.
A limit order adds liquidity to the order book: a buy order is placed below the price, a sell order above. You choose the price but not the moment — the order may never fill.
Traders who place limit orders are makers and usually pay lower fees than takers (see maker and taker).
On HyperScan
On the coin pages of the liquidation map HyperScan shows large whale limit orders together with their stop-losses and take-profits.