The close strength line shows how much the strength in the current up/down trend actually present. We calculate it by difference between High-Low and the way it moves with respect to Close moving averages. You can change intervals from settings. Use this in combination with any other moving average indicator e.g. EMA 13 when Close line is below other indicators/priceline, it is Uptrend and close line acts as support. when Close line is above other indicators/priceline, it is Downtrend and close line acts as resistance.
You can also use Close line as potential Targets for Buy or Short trades depending on it's direction with respect to price line last Close.