Based on the source.
https://www.tradingview.com/script/JkqUNW7J/The Forecast Oscillator is a technical indicator that compares a security close price to its time series forecast.
If the Forecast Oscillator stays above the zero line for an extended period, then it signals that the price may rise in the future and if it stays below the zero line for an extended period, then it signals a coming fall in the security price.