When it rains, the amount of rain fall is measured by the level of filling of a vessel. Suppose that the vessel is a circular bucket placed in a square container. What is the probability that a drop falling into the container ends up in the bucket?
The frequency gives an estimate of the probability which is better and better as long as the number of simulated drops increases. Consider the number and find the better approximation of its value you can obtain (eventually computing a suitable mean of many values). Which value you find? How can you interpret the result you get?