The basic idea
Hedging means taking a position designed to offset the risk of another position you hold. The classic example outside trading is a business that will receive foreign currency in the future taking an offsetting position now, so that whichever way the exchange rate moves, its overall outcome is more predictable.
The purpose of a genuine hedge is to reduce uncertainty, not to make a profit. It trades away potential upside in exchange for protection against downside. That trade-off is the essence of hedging and the part beginners often miss.
What hedging costs
Hedging is not free. Holding offsetting positions means paying spreads on both, and potentially swap charges on both, while your net market exposure is small or zero. If you hedge fully, you have largely locked in your current situation and are paying for the privilege.
This is why a hedge is a tool for managing a specific, understood risk, not a way to make money appear. A perfectly offsetting hedge that costs money each night is simply an expensive pause — sometimes worthwhile, but never a free profit.
The beginner misunderstanding
Some beginners open an offsetting position on a losing trade, hoping to "freeze" the loss and sort it out later. In practice this often just doubles the costs and the complexity while doing nothing to resolve the original problem — you still have to decide when and how to unwind both sides.
More often than not, if a trade has gone wrong, simply closing it is cleaner and cheaper than layering a hedge on top. Hedging has legitimate uses for those with specific exposures to manage, but as a reflexive response to a losing trade it usually adds confusion rather than protection. Understand exactly what risk you are offsetting before you hedge anything.