P value is the probability that you are wrong if you reject the null hypothesis.

or

P value is the probability that you get equal or worse result if your experiment is right…

or according to Wikipedia:

For example, if you propose a hypothesis that Trump has more positive tweets than Hillary has, the your data tells you p = 0.03, then the probability that Trump has same or less positive tweets than Hillary is 0.03.

The p value does not directly mean how likely what the null hypothesis describes happens in your experiment. It tells us how unlikely your observations happen if you assume that the null hypothesis holds.