In this position, funds are bought by the trader and then sold at the target Price. Traders open a long position in the hope that the price will go up in the future. It is the most common way to invest with the underlying assumption that the value of the asset will increase over a period of time by simply buying and holding.
E.g., if a trader, trading in the XRP/BTC pair, longs 1000 XRP at 2x leverage. If the BTC equivalent of 1000 XRP is 0.09 BTC (considering XRP/BTC is at 0.00009000), then the exchange collects a collateral of 0.045 BTC only. Thus, allowing 2x leverage.
In this long position, exchange forwarded 0.045 BTC to the trader for buying 500 XRP, in addition to the 0.045 BTC held by the trader.