This is a powerful knowledge for those who trade more currency pair correlation trading forex one currency pair. It helps to hedge, diversify or double profitable positions.
A correlation of zero means no relation between currency pairs exists. Information about current correlation coefficients can be found here: Currency Correlations Table. How a trader can use this information? A very simple use is avoiding trades that cancel each other. However, there is a strategy of hedging one currency pair with another. For example, a trader has opened long positions on both currency pairs.