This is a HL7 FHIR server, and as you appear to be accessing this page from a web browser you are seeing a HTML version of the requested resource(s). You can also access this URL from a FHIR client as a ReSTful API call. For more details please see the HL7 FHIR specification.
<CodeSystem xmlns="http://hl7.org/fhir">
   <id value="CareConnect-LanguageAbilityProficiency-1"></id>
   <text>
      <status value="generated"></status>
   </text>
   <url value="https://fhir.hl7.org.uk/STU3/CodeSystem/CareConnect-LanguageAbilityProficiency-1"></url>
   <version value="1.1.0"></version>
   <name value="Care Connect Language Ability Proficiency"></name>
   <status value="draft"></status>
   <date value="2018-11-01T00:00:00+00:00"></date>
   <publisher value="HL7 UK"></publisher>
   <description value="A CodeSystem to identify the level of proficiency in communicating a language."></description>
   <copyright value="Copyright © 2016 HL7 UK"></copyright>
   <caseSensitive value="true"></caseSensitive>
   <content value="complete"></content>
   <concept>
      <code value="E"></code>
      <display value="Excellent"></display>
   </concept>
   <concept>
      <code value="F"></code>
      <display value="Fair"></display>
   </concept>
   <concept>
      <code value="G"></code>
      <display value="Good"></display>
   </concept>
   <concept>
      <code value="P"></code>
      <display value="Poor"></display>
   </concept>
</CodeSystem>