Why there is some function is recursive, what is the role of recursive.

For example like in COUNT_RECURSIVE,
When I call the function without recursive, I get only two variables but with recursive 8, that mean recursive count everything inside the arrays?

If the optional mode parameter is set to COUNT_RECURSIVE (or 1), count() will recursively count the array. This is particularly useful for counting all the elements of a multidimensional array.

A recursive function is a function that calls itself.Sometimes the easiest way to model a problem is to make a function call itself a technique known as recursive function calling.