<?php
/**
 * Display the number of items published by the current user.
 *
 * @param   int  $userId  The user ID.
 * @return  string
 */

function k2_user_items_count($userId) {
    $db = JFactory::getDbo();
    $db->query('COUNT(*) FROM #__k2_items WHERE created_by = '.$userId);
    $db->setQuery($query);
    $numItems = $db->loadResult();
    return $numItems;
}

// Get the current user ID
$userId = (int) JFactory::getUser()->id;

// Count the number of items published by the current user
$numItems = k2_user_items_count($userId);

// Display the number of items
echo '<span>' . $numItems . '</span>';