From Confidence level, select the level of confidence for the confidence intervals for the regression coefficients. The confidence intervals (CI) are ranges of values that are likely to contain the true value of the coefficient for each term in the model.
Usually, a confidence level of 95% works well. A 95% confidence level indicates that if you took 100 random samples from the population, the confidence intervals for approximately 95 of the samples would contain the true value of the coefficient. For a given set of data, a lower confidence level produces a narrower interval, and a higher confidence level produces a wider interval.