these are the references you need :
Name: Edward Cocks
Registration district: Skibbereen
Event type: Marriage
Quarter and year Jan-Mar 1884
Volume: 5 / Page: 523
a matching entry appears for an Ellen Northridge, so a possible cross-match
other details on FamilySearch or Ancestry (e.g. film number etc), are internal references, and not relevant to the GRO.
Shane