Although used in pirates of the carribean, it originated from the french verb meaning "to speak" which is actually "parler." Parlez is the vous(you plural i.e. y'all/you guys)form, also used as the command form. In pirates of the carribean it is used as the right to speak to and negotiate terms with the captain, etc.
Je parle! (I speak) Elle lui parle a.(She speaks to him/her) I invoke the right of parlez. (as used in POTC)