Quotes for trading instruments usually have two sides: the bid price and the ask (offer) price. The bid price is the price of an asset at which the market or broker is ready to buy from a trader (that is, the trader can sell, or go short, at this price). The Ask or Offer price is the price at which a trader can buy an asset.
Spread is the difference between the Bid and the Ask price.
Example: The quoted EURUSD rate at the moment is 1.30290/1.30303. This means that 1.30290 is the bid price – a trader can sell EURUSD at this price, whereas 1.30303 is the ask price – a trader can buy EURUSD at this price. The Spread is 1.3 pips (Bid – Ask = 1.30303 – 1.30290 = 0.00013 points or 1.3 pips).