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>
    <allmessages>
      <message name="ipb-blockingself" xml:space="preserve">You are about to block yourself! Are you sure you want to do that?</message>
      <message name="ipb-blocklist" xml:space="preserve">Blokeaketak ikusi</message>
      <message name="ipb-blocklist-contribs" xml:space="preserve">$1(r)en ekarpenak</message>
      <message name="ipb-change-block" xml:space="preserve">Berriz blokeatu erabiltzailea, parametro hauekin</message>
      <message name="ipb-confirm" xml:space="preserve">Blokeoa baieztatu</message>
      <message name="ipb-confirmaction" xml:space="preserve">If you are sure you really want to do it, please check the &quot;{{int:ipb-confirm}}&quot; field at the bottom.</message>
      <message name="ipb-confirmhideuser" xml:space="preserve">You are about to block a user with &quot;hide user&quot; enabled. This will suppress the user's name in all lists and log entries. Are you sure you want to do that?</message>
      <message name="ipb-default-expiry" xml:space="preserve" />
      <message name="ipb-disableusertalk" xml:space="preserve">Galarazi erabiltzaile honi bere eztabaida orria editatzea, blokeatuta dagoen aldian</message>
      <message name="ipb-edit-dropdown" xml:space="preserve">Blokeatzeko arrazoiak aldatu</message>
      <message name="ipb-hardblock" xml:space="preserve">Galarazi izena emandako erabiltzaileek IP helbide honetatik editatzea</message>
      <message name="ipb-needreblock" xml:space="preserve">$1 dagoeneko blokeaturik dago. Ezarpenak aldatu nahi al dituzu?</message>
      <message name="ipb-otherblocks-header" xml:space="preserve">Bestelako {{PLURAL:$1|blokeoa|blokeoak}}</message>
      <message name="ipb-unblock" xml:space="preserve">Erabiltzaile izen edo IP helbide bati blokeoa kendu</message>
      <message name="ipb-unblock-addr" xml:space="preserve">$1 lankide edo IP helbideari blokeoa baliogabetu</message>
    </allmessages>
  </query>
</api>