it means that the differences between the rates at which you can buy or sell a currency constantly change as the conditions of the forex market change. If the market is not volatile, then you can easily get a spread range of 1 to 4 pips for the EUR/USD pair. This rate shoots up to 8 pips if the market becomes unstable.

A real spread of the interbank Forex market with an accuracy of 5 decimal places.

Changes in a currency's value relative to another currency (or currencies).