Statistics. The P value is a probability, with a value ranging from 0 to 1 and used in statistical significance testing. Hypotheses which are formulated before study start can be evaluated by statistical significance tests. The null hypothesis (H0) is the thesis, that the difference, as proposed in the alternative hypothesis, in a specific research question does not exist.
If the p-value is less than the significance level alpha, which is often 0.05, the null hypothesis is rejected and the result is said to be "statistically significant".