What does it mean?
As a web developer, functions.php is a crucial file in WordPress that contains all the necessary functions and code snippets required to enhance the functionality of a website. It is a PHP file that is located in the theme folder and is responsible for adding new features, modifying existing ones, and customizing the theme's behavior. The functions.php file is loaded automatically by WordPress and is executed before any other template files, making it an ideal place to add custom code. It is used to register custom post types, create custom taxonomies, enqueue scripts and styles, add custom menus, and much more. In short, functions.php is the backbone of a WordPress theme, and any customization or modification to the theme's functionality is done through this file.