What is the use of PHP declaration global variables outside of the function

What's the use of PHP declaring a global variable outside of a function?
What's the use of PHP declaring a global variable outside of a function?

I see the WordPress wp-settings.php file in this paragraph:

/*
* These can ' t be directly globalized in version.php. When updating,
* we ' re including version.php from another install and don ' t want
* These values to be overridden if already set.
*/
Global $WP _version, $wp _db_version, $tinymce _version, $required _php_version, $required _mysql_version;
Require (Abspath. Wpinc. '/version.php ');

I don't understand, I beg to explain, thank you ^_^ have no effect
And I didn't see it in the wp-settings.php.
Global $WP _version, $wp _db_version, $tinymce _version, $required _php_version, $required _mysql_version;
Only
Require (Abspath. Wpinc. '/version.php '); no effect.

