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.
<?xml version="1.0" encoding="UTF-8" standalone="no"?><ValueSet xmlns="http://hl7.org/fhir">
   <id value="CareConnect-MedicationPrescribingAgency-1"/>
   <url value="https://fhir-test.hl7.org.uk/STU3/ValueSet/CareConnect-MedicationPrescribingAgency-1"/>
   <version value="1.0.0"/>
   <name value="Care Connect Medication Prescribing Agency"/>
   <status value="draft"/>
   <date value="2019-12-05T17:01:00+00:00"/>
   <publisher value="HL7 UK"/>
   <description value="A ValueSet to identify the prescribing agency."/>
   <copyright value="Copyright © 2019 HL7 UK"/>
   <compose>
      <include>
         <system value="https://fhir-test.hl7.org.uk/STU3/CodeSystem/CareConnect-MedicationPrescribingAgency-1"/>
      </include>
   </compose>
</ValueSet>