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>
    <namespaces>
      <ns id="-2" case="first-letter" canonical="Media" xml:space="preserve">Media</ns>
      <ns id="-1" case="first-letter" canonical="Special" xml:space="preserve">Special</ns>
      <ns id="0" case="first-letter" content="" xml:space="preserve" />
      <ns id="1" case="first-letter" subpages="" canonical="Talk" xml:space="preserve">Discuție</ns>
      <ns id="2" case="first-letter" subpages="" canonical="User" xml:space="preserve">Utilizator</ns>
      <ns id="3" case="first-letter" subpages="" canonical="User talk" xml:space="preserve">Discuție Utilizator</ns>
      <ns id="4" case="first-letter" subpages="" canonical="Project" xml:space="preserve">MusicLexis</ns>
      <ns id="5" case="first-letter" subpages="" canonical="Project talk" xml:space="preserve">Discuție MusicLexis</ns>
      <ns id="6" case="first-letter" canonical="File" xml:space="preserve">Fișier</ns>
      <ns id="7" case="first-letter" subpages="" canonical="File talk" xml:space="preserve">Discuție Fișier</ns>
      <ns id="8" case="first-letter" subpages="" canonical="MediaWiki" xml:space="preserve">MediaWiki</ns>
      <ns id="9" case="first-letter" subpages="" canonical="MediaWiki talk" xml:space="preserve">Discuție MediaWiki</ns>
      <ns id="10" case="first-letter" canonical="Template" xml:space="preserve">Format</ns>
      <ns id="11" case="first-letter" subpages="" canonical="Template talk" xml:space="preserve">Discuție Format</ns>
      <ns id="12" case="first-letter" subpages="" canonical="Help" xml:space="preserve">Ajutor</ns>
      <ns id="13" case="first-letter" subpages="" canonical="Help talk" xml:space="preserve">Discuție Ajutor</ns>
      <ns id="14" case="first-letter" canonical="Category" xml:space="preserve">Categorie</ns>
      <ns id="15" case="first-letter" subpages="" canonical="Category talk" xml:space="preserve">Discuție Categorie</ns>
    </namespaces>
  </query>
</api>