What are the units of P and V when R is expressed in terms of J/(mol K)?
Would you agree that pressure is expressed as a force acting on a surface? If so, let's juggle with units and start with the pascal. 
$1\ \mathrm{Pa} = 1\ \mathrm{Nm^{-2}}$
will certainly be familiar to you ;)

Would you further agree that we can express the joule as $1\ \mathrm J = 1\ \mathrm{Nm}$?