In any regression model, the R² (R-squared) value is a key performance metric, and the bigger the R² value, the better the prediction.
Here's how to interpret the R2 value:
R2 = 1 -> Perfect prediction. The model explains all the variability of the target variable.
R2 = 0 -> The model does no better than simply predicting the mean of the target.
R2 < 0 -> The model is worse than using the mean as a prediction.
So, your value of 0.8 is close to a good prediction.