Ask — a price asked for the sale of certain equity. Also, known as the offer price. In trading, it is a price, which traders name for the purchase of a currency.
The market functions following the bid/ask auction. The buyer indicates the price he's going to pay for the asset. Then, the seller names the final price. This is the ask price. The buyer looks through the different variants and chooses the lowest price among others.
The trader needs to know these prices to consider this difference when he sets the stop-losses or plans the profit.