In futures, it can trade in both directions, either long or short. Among them, to put it more generally, you estimate that its price will rise in the future, so you choose to buy at a low price, and then wait for the future price to rise and sell at a profit.

The antonym of long is short. To put it bluntly, shorting means: you expect its price to fall in the future, so you choose to borrow some products to sell at high prices, and then wait for the future price to fall, then buy the same products and return to make a profit.