A Short Trade is initiated by borrowing an asset from your broker to sell it with the intention to buy back at a lower price to make a profit and return the borrowed asset back to your broker.
Let's say you borrowed 0.1ETH when Ethereum was at $1,500, you get $150 to reinvest when Ethereum falls to $1,000. At this price point, the investment is worth 0.15ETH, leaving you with a profit of 0.05 after paying interest.
A Long Trade is initiated by buying an asset with the expectation that the price of the assets will go up from a given point and make a profit.
In a nutshell, long and short ponder on whether a trader believes a cryptocurrency is going to rise or fall in value
Also, it is being said that during the bull market, you will see more long positions than short as traders will want to benefit from the price fluctuation, while in a bearish market short positions exceed the long position.