How do I programmatically add text to a page?
You're looking for the page callback, which is:


  The function to call to display a web page when the user visits the path. If omitted, the parent menu item's callback will be used instead.


For example:

function sky_view_menu() {
  $items['admin/skyview'] = array(
    'title' =&gt; 'Skyview Settings',
    'type' =&gt; MENU_NORMAL_ITEM,
    'access callback' =&gt; TRUE,
    'page callback' =&gt; 'MYMODULE_skyview_admin_page',
  );

  $items['admin/skyview/tab1'] = array(
    'title' =&gt; 'Skyview',
    'type' =&gt; MENU_DEFAULT_LOCAL_TASK,
    'access callback' =&gt; TRUE,
    'weight' =&gt; 0,
    'page callback' =&gt; 'MYMODULE_skyview_admin_tab_1',
  );
  ...
  return $items;
}

function MYMODULE_skyview_admin_page() {
  return [
    '#markup' =&gt; t('Hello world'),
  ];
}

function MYMODULE_skyview_admin_tab_1() {
  return [
    '#markup' =&gt; t('Hello tab 1'),
  ];
}


The function name itself is arbitrary, but for the sake of sanity it's best to name it as something that represents the route behind it.