The purpose of this model is to demonstrate that, although the probability of getting either a head or a tail is 0.5, this doesn't mean that you will get equal numbers of heads and tails in a small sample size. If you were to toss 1000 coins, however, you would get closer to a 500:500 split. You could try that yourself by modelling it in Excel!
Number of heads: Number of tails:
You can learn more about generating and scaling random numbers in the Interactive section.