How to add notification bubble to Wordpress admin menu

Following process will add pending post count in admin menu items..
You also can change as your need..

Edit the theme's `function.php` and add following line of code :-

First, add hook to admin menu

//Add hook to Admin Menu.
add_action('admin_menu', 'notification_count_in_admin_menu');

Now add function that will alter you menu with notification count.

function notification_count_in_admin_menu()
{
    global $menu;
    $post_types = array('post', 'page', 'your_cpt');
    foreach ($post_types as $type)
    {
        $post_count = get_number_of_pending_post_by_type($type);
        if(!empty($post_count))
        {
            foreach ( (array)$menu as $key => $parent_menu )
            {
                if ( $parent_menu[2] == 'edit.php?post_type='.$type )
                {
                    $menu[$key][0] = $menu[$key][0]. ''.$post_count.'';
                }
            }
        }
    }
}
function get_number_of_pending_post_by_type($type)
{
    global $wpdb;
    return $wpdb->get_var( "SELECT COUNT(ID) as count FROM {$wpdb->post} WHERE `post_status`='pending' AND `post_type`='{$type}';" );
}

Have fun!