They could use the ideas established in the quotation to show how others also support the same belief they do, the quotation could also logically support their viewpoint or easily sums up the argument/perspective they hold.
A noun clause is a dependent clause that acts as a noun. Noun clauses begin with words such as how, that, what, whatever, when, where, whether, which, whichever, who, whoever, whom, whomever, and why. Noun clauses can act as subjects, direct objects, indirect objects, predicate nominatives, or objects of a preposition.
We would need a paragraph or story but tthe best i can tell you is look at the surroding words and how that word is being used and pull out details that think is important for that useage of that word