Swing Trading -Buy
In Swing Trading, as with all other kinds of trading, the aim is to make profits.
When a trader goes long, the aim is to sell the bought currency at a higher rate than what it was bought at.
If GBP/USD was traded and the trader went long then it means they bought GBP using USD. At the time of closing the trade, if the exchange rate rises they will be able to get more USD in return for selling GBP. That difference is their profit.