Range is the difference between a market’s highest and lowest price in a given period. It is mostly used as an indicator of volatility: if a market has a wide range, it's a sign that it was volatile over the period analyzed.
Trading foreign exchange on margin carries a high level of risk, and may not be suitable for all investors. Before deciding to trade foreign exchange you should carefully consider your investment objectives, level of experience, and risk appetite. You could sustain a loss of some or all of your initial investment and should not invest money that you cannot afford to lose. CFDs are complex instruments and come with a high risk of losing money rapidly due to leverage.