WordPress at a glance
action is not described

change_locale action-hook . WP 4.7.0

Fires when the locale is switched to or restored.

Usage

add_action( 'change_locale', 'action_function_name_5373' );
function action_function_name_5373( $locale ){
	// action...
}
$locale(string)
The new locale.

Where the hook is called

WP_Locale_Switcher::change_locale()
wp-includes/class-wp-locale-switcher.php 233
do_action( 'change_locale', $locale );

Where the hook is used (in WP core)

wp-includes/default-filters.php 464
add_action( 'change_locale', 'create_initial_post_types' );
wp-includes/default-filters.php 497
add_action( 'change_locale', 'create_initial_taxonomies' );