What does a p value less than 0.05 mean?

A p-value less than 0.05 indicates that there is strong evidence against the null hypothesis, suggesting that the observed data is unlikely to have occurred by random chance alone if the null hypothesis were true. This typically leads researchers to reject the null hypothesis in favor of an alternative hypothesis. However, it does not measure the size or importance of an effect, nor does it confirm that the alternative hypothesis is true. It's essential to consider the context and the study design when interpreting p-values.