Change page title of a module generated page
The module is using its own menu definition. The title of the menu item is used for displaying the page title of the page in question (which is 'Tags' in English and 'Labels' in your Dutch version):

/**
 * Implements hook_menu().
 */
function tagclouds_menu() {
  $items = array();

  // [...]

  $items['tagclouds/list/%tagclouds_vocs'] = array(
    'title' =&gt; 'Tags',
    'page callback' =&gt; 'tagclouds_page_list',
    'page arguments' =&gt; array(2),
    'access callback' =&gt; 'user_access',
    'access arguments' =&gt; array('access content'),
    'type' =&gt; MENU_CALLBACK,
  );

  // [...]

  return $items;
}


As you are using a localized version of Drupal, you have several options to change the page title.

The first and most easy solution is to change the translation of 'Tags' to your desired string. You can use the localization interface which is located at /admin/config/regional/translate/translate.

However, the above solution will change the translation for 'Tags' within your whole site. Which means that the new translation might appear somewhere else as well, and on an English page the title would still be 'Tags'.

The second solution is changing the menu item's title. You can do so without side-effects as the menu item of question is a menu callback. Its title will not be shown within your menu structure, but as page title only. As you should never touch the sources of a contributed module (for your customizations), writing a small custom module is the way to go here.

Follow this guide to get started with custom modules and create the required files. Within your custom module's MYMODULE.module file you can implement hook_menu_alter(), which allows you to change the menu items of other modules. In this case, we'll change the menu item of the tagclouds tag overview page:

/**
 * Implements hook_menu_alter()
 */
function MYMODULE_menu_alter(&amp;$items) {
  // Whether the tagclouds menu item is defined.
  if (isset($items['tagclouds/list/%tagclouds_vocs'])) {
    // Change the menu item's title.
    $items['tagclouds/list/%tagclouds_vocs']['title'] = 'Your New English Title';
  }

  // For translation extractors, you may also implement
  // this little function call.
  t('Your New English Title');
}


Change MYMODULE to your module's name, activate the module and/or clear your Drupal caches. You might have to visit the page once, so that the translatable string will be known to Drupal's localization system. Afterwards you can head to the translation interface as described within the first solution and add a translation for 'Your New English Title'.

The third solution is to hook into the page pre-processing within your theme. Locate your theme's template.php file. If your theme is implementing the theme hook THEME_preprocess_page() already (which is very likely), you may just add the lines from the following function's body. If your theme does not implement this hook, you may add the whole function, renaming THEME to your theme's name. This little code checks, whether you are at the tagclouds listing page and - if so - changes the page title using drupal_set_title():

/**
 * Implements THEME_preprocess_page()
 */
function THEME_preprocess_page(&amp;$variables) {
  // Load the current path into a variable.
  $current_path = current_path();
  // Whether the current path is the tagclouds listing path.
  if (strpos($current_path, 'tagclouds/list/') === 0) {
    // Set the page title. We use drupal_set_title here, as
    // the static page title will be evaluated within the
    // process_page function, which follows the pre-processing.
    drupal_set_title(t('Your New English Title'));
  }
}


Once again, following Drupal standards you set the English title here, so after you cleared the Drupal caches and visited the page once, you should follow the steps of the first solution to add an appropriate Dutch translation to your localization.

The last solution is suggesting the module maintainer to allow editing the page labels within the module settings. This change however might take a little longer as most module maintainers are contributing to the modules within their spare time.