Long refers to the position taken by an investor with the intent of getting a huge exposure in the near future. A long position is taken for a longer duration of time. It is the exact opposite of taking a short position, where the investor believes in asset depreciation. With short positions, investors try to capitalize on the downturn.
There are several instances where crypto enthusiasts took a long position on tokens while holding them for years. The same long and short positions can also be taken without directly owning the asset. This can be achieved in the derivative market using financial instruments such as futures and options.