The p value is the risk of getting an effect specifically due to sampling error, under the assumption of perfectly random sampling with no real effect. It says very little.

In particular, if you aren't doing perfectly random sampling it is meaningless. If you are concerned about other types of error than sampling error it is meaningless.

A significant p-value is nowhere near proof of effect. All it does is suggestively wiggle its eyebrows in the direction of further research.