Comparator , Functor Internal Working

Sir,
How does the priority_queue interpret return value from comparator / functor to arrange the data in the priority_queue ?
And also explain about the arguments that a function implicitly passes into a comparator ?

priority queue uses the comparator as a compare function
at basic step when it have to make a choice between 2 data items it calls the comparator,
(if explicitly defined) and choose based on true or false value form it.

this implementation is not needed in Competitive programming, you need to know how to use it.

and what arguments you want to know?
not able to understand your last line