A Reference Source is usually a physical or digital document that you would refer to for more information about a topic. Examples include dictionaries (refer to for definitions of words) and encyclopedias (refer to for broad summaries about a topic).
These documents are referred to, rather than read cover-to-cover. They are typically information-dense and factual, written as unbiased as possible.
Each HCC Library usually has a Reference Section, where reference sources are kept for in-library use.