The most important value ...

This is an example of what was meant by the earlier statement regarding the most important value of an array and the ability to use another variable as the index to iterate through the array elements in a controlled fashion.

In this case, the variable is the loop counter named count.

As the value of count is decremented once during each iteration of the loop, incoming values from the user are stored successively in array elements 4, 3, 2, 1, and 0.