PVR stands for "Personal Video Recorder", sometimes known as the DVR (Digital Video Recorder).
Rather than recording onto VHS video cassettes, a PVR records TV programmes onto a hard disk that's usually built into a set-top box. Sometimes you can add an external hard disk.
There are several advantages to using a PVR to record your favourite TV shows: no tapes to rewind, the ability to pause live TV, integrated programme guides. Plus a lot more storage space than a standard VHS cassette.