How to add custom menu item to the WordPress nav menu

The content between the li tags could be anything You want!

For example shortcode for language switcher, social icons or custom text.

// =========================================================================
// ADD CUSTOM MENU ITEM TO THE WORDPRESS NAV MENU
// =========================================================================
function add_custom_menu_item ($items, $args) {
    $items .= '<li id="menu-item-5000" class="menu-item menu-item-type-post_type menu-item-object-page last">';
        $items .= 'Last Menu Item';
    $items .= '</li>';
    return $items;
}
add_filter( 'wp_nav_menu_items', 'add_custom_menu_item', 10, 2 );