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="Obr_cov_3.png|98" />
  </query-continue>
  <query>
    <pages>
      <page pageid="44" ns="0" title="Maximální přípustné hodnoty faktoru ochranného vlivu vegetace (Cp)" />
      <page pageid="55" ns="0" title="LFA" />
      <page pageid="98" ns="0" title="Čistírny odpadních vod" />
      <page pageid="47" ns="0" title="GAEC 2" />
      <page pageid="48" ns="0" title="GAEC 5" />
      <page pageid="49" ns="0" title="GAEC 8" />
      <page pageid="40" ns="0" title="Vodní eroze" />
      <page pageid="50" ns="0" title="Bodová výnosnost" />
      <page pageid="94" ns="0" title="Energetická spotřeba v lokalitě" />
    </pages>
  </query>
</api>