Final answer:
A property reference of .Language(Spanish) in a candidate case signifies the use of a Page Group property to capture a candidate's language skills.
Step-by-step explanation:
When capturing a candidate's language skills in a candidate case, if the property reference is .Language(Spanish), the type of property used is a Page Group. This is because the syntax suggests that the language skill being captured (in this case, Spanish) is part of a group or a list of languages that the candidate might have. A Page Group property allows each language to be indexed by a distinguishing value, which, in this scenario, is the name of the language itself, such as 'Spanish'.