Closing a position means that you now have a stock, a future positions and a foreign exchange currency pair. If you don't want to hold it any more, sell it. However, because some investments are sold by telegram in the process of buying, it is not appropriate to sell them later, so everyone is used to calling them liquidation, that is, to sell what you have.

Selling gold is short selling. For example, if you think the price of cabbage will fall, you borrow someone else's cabbage and sell it first, and then buy it back to him when his price comes down. That's what it means. The example may not be appropriate.