It's a variation upon VOR/DME.
The aircraft is equipped with a navigation system which allows you to define artificial waypoints in terms of a VOR radial and a DME distance. It will then display those on the CDI and DME readout (using a bit of basic trig that is easy for a small computer, but too complex to do manually whilst flying) as if each waypoint was a discrete VOR/DME transmitter in it's own right.
I'm not an instrument pilot, but I'd guess in the context of a STAR chart that it's requiring you to have the ability to define a user waypoint in your nav box allowing you to fly the approache referenced to a defined point in space.
GPS will do the same thing equally well of-course, but is not necessarily approved for primary nav in most parts of the world. But, in a fit of pragmatism, most airfield plates will show VRPs as both a lat-long (GPS or INS) and as a VOR/DME relationship so effectively either (or both) is/are useable.
In light aircraft the King KNS-80 is probably the most commonly found RNAV device and used in a lot of training establishments. If the kit is fitted into many school PA28s and C172, it's probably a reasonable guess that you'll find something that'll do the job in most 737s - I'm sure there's a 737 driver in the house who can confirm or deny that.
G