Why is it important for PHP developers to have a good understanding of arrays and how can they improve debugging by using print_r() function?

It is important for PHP developers to have a good understanding of arrays because arrays are a fundamental data structure in PHP used to store multiple values in a single variable. By understanding arrays, developers can efficiently manipulate and access data in their applications. The print_r() function is a useful tool for debugging PHP code as it allows developers to inspect the contents of arrays and other variables, helping them identify and resolve issues more quickly.

```php
// Example PHP code snippet demonstrating the use of print_r() function for debugging arrays

$fruits = array("apple", "banana", "orange");
print_r($fruits);
```

In the above code snippet, we have an array named `$fruits` containing three fruit names. By using `print_r($fruits)`, we can output the contents of the array to the browser or console, making it easier to debug and understand the data structure.