You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allfileusages gafcontinue="BWHammerSickle.jpg|4683" />
  </query-continue>
  <query>
    <pages>
      <page pageid="4431" ns="0" title="Sport in Astana" />
      <page pageid="4539" ns="0" title="BC Astana" />
      <page pageid="4684" ns="0" title="Red star" />
      <page pageid="5190" ns="0" title="European route E40" />
      <page pageid="7553" ns="0" title="Prime Minister of Kazakhstan" />
      <page pageid="7680" ns="0" title="Metre Convention" />
      <page pageid="7934" ns="0" title="Armed Forces of the Republic of Kazakhstan" />
    </pages>
  </query>
</api>