Hedging is opening of positions on the same market to compensate for the impact of the possible price risks that come from an equal, but an opposite position on another market. Usually hedging is done in order to avoid risks that come with price changes. Example: you can open a long position in EURUSD and a short one in the same instrument.

MT5 accounts allow you to choose whether the account will be a hedging or netting account when opening it.