In a long position, you expect the price of a crypto asset to rise. In a short position, you expect it to fall.
To go long in CFD trading, you buy a CFD representing the underlying asset in hopes of selling it later once the price increases. To go short, you do the opposite, selling the CFD with the intention of buying it back later at a lower price. In both cases, your profit corresponds to the difference between your entry and exit points, regardless of whether the market moves up or down.