Network Value to Transactions Ratio (NVT) is defined as the ratio of market capitalization divided by transacted volume. NVT Ratio can be thought of as an indicator that measures whether the blockchain network is overvalued or not. If it is upper than red line, it means overvalued.
NVT Golden Cross targets to generate short or long signals by comparing the short-term trend of NVT and the long-term trend of NVT. If the short-term trend is way greater than the long-term trend is, the network can be interpreted as overpriced and will soon revert to mean value, meaning short signal. Similarly, the opposite case may imply a long signal. Over the red line is short signal and under the green line is long signal.