Spread
The spread is the gap between the buy price and the sell price, and it is the first cost of every trade.
A spread of 1.2 pips on a standard lot of EURUSD costs about 12 US dollars to open and close a position.
Spreads widen when the market is thin or news is due. The advertised average is not what you pay at 22:00 or during a release.
Related terms
A definition, not financial advice. Trading carries a risk of loss.