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>
    <pageswithprop gpwpcontinue="55" />
  </query-continue>
  <query>
    <pages>
      <page pageid="6" ns="0" title="Θέματα Ενδιαφέροντος για τις Κατηγορίες των Χρηστών του GAIA" contentmodel="wikitext" pagelanguage="el" touched="2016-06-21T06:59:34Z" lastrevid="7" counter="4036" length="849" new="" />
      <page pageid="10" ns="0" title="Αγροτικοί Τομείς" contentmodel="wikitext" pagelanguage="el" touched="2019-05-30T10:02:44Z" lastrevid="53786" counter="31361" length="1149" />
      <page pageid="12" ns="0" title="Θεματικές Περιοχές Πληροφόρησης" contentmodel="wikitext" pagelanguage="el" touched="2020-11-30T11:46:43Z" lastrevid="59629" counter="26589" length="3373" />
      <page pageid="15" ns="0" title="Thanos" contentmodel="wikitext" pagelanguage="el" touched="2018-05-02T11:24:13Z" lastrevid="59151" counter="416975" length="74348" />
      <page pageid="40" ns="0" title="Συλλογικές αγροτικές οργανώσεις" contentmodel="wikitext" pagelanguage="el" touched="2013-12-30T07:08:14Z" lastrevid="41" counter="5363" length="1527" new="" />
      <page pageid="43" ns="0" title="Σύμβουλοι Παραγωγής, Μελετητές, Επιθεωρητές" contentmodel="wikitext" pagelanguage="el" touched="2013-12-30T07:08:14Z" lastrevid="11858" counter="4559" length="60" />
      <page pageid="45" ns="0" title="Επιχειρήσεις" contentmodel="wikitext" pagelanguage="el" touched="2013-12-30T07:08:14Z" lastrevid="46" counter="5878" length="740" new="" />
      <page pageid="47" ns="0" title="Οργανισμοί, Πανεπιστήμια, Φορείς" contentmodel="wikitext" pagelanguage="el" touched="2016-06-30T08:53:02Z" lastrevid="11874" counter="5949" length="61" />
      <page pageid="48" ns="0" title="Καταναλωτές, Ενώσεις Καταναλωτών" contentmodel="wikitext" pagelanguage="el" touched="2016-06-21T06:59:34Z" lastrevid="29896" counter="5755" length="1789" />
      <page pageid="54" ns="0" title="Κτηνοτρόφοι" contentmodel="wikitext" pagelanguage="el" touched="2016-10-04T10:11:24Z" lastrevid="56437" counter="3797" length="2572" />
    </pages>
  </query>
</api>