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>
    <allpages>
      <p pageid="19" ns="0" title="Como Acessar Meus E-mails?" />
      <p pageid="15" ns="0" title="Como acessar meus e-mails?" />
      <p pageid="29" ns="0" title="Como enviar meus arquivos pelo cPanel?" />
      <p pageid="18" ns="0" title="Criando contas de e-mail" />
      <p pageid="3" ns="0" title="Criando um Banco de Dados" />
      <p pageid="1" ns="0" title="Main Page" />
      <p pageid="20" ns="0" title="Microsoft Outlook 2013" />
      <p pageid="35" ns="0" title="Onde coloco os meus arquivos?" />
      <p pageid="12" ns="0" title="Página principal" />
    </allpages>
  </query>
</api>