Typically it is thought of Public Relations..."s" on the end.
"public relations" 82.200 mil
"public relation" 1.290 mil
"public relations agency" 444K
"public relation agency" 773 (seven hundred seventy three)
Perhaps you can see what just the omission of one letter can do to a domain name and a search term (done on google, by the way).
Overture:
51347 public relations
1334 public relations agency
57 agency public relation
Not even a count for Public Relation Agency or even Public Relation.
Parked it could be used as a common typo perhaps.
As a domain straight up to re-sell? Not much if the buyer does a search like I have just demonstrated.
Developed as a portal site for Public Relations Agencies? or start you own site with branding of your own domain? Who knows...but as is, it is really not much and will not bring much traffic.