When you throw a coin 100 times, each sequence you get is equally likely. However. You can look at properties of the sequence which are more likely to be one way than the other. For instance, it's more likely that the number of heads and tails are about equal than not. The reason is that there are more sequences, in general, where that is true, than those where heads or tails strongly prevail.
With the right property, you can make statements such as: This sequence is statistically likelier to be human made than random.
One such property is for instance the number of changes from heads to tails, or vice versa. In expectation, random sequences change heads to tails about 50% of all flips. For humans, the expectation is much higher. Hence, if you compare two sequences where one has 51% changes and one 63%, it is mathematically (/statistically) accurate to say that the latter one is likelier human made.