POV is the acronym for Point of View and with relation to writing this refers to the person whose perspective the author is writing from.
It used to be fairly common to write from an omniscient POV, however in recent years editors have begun to frown on the use of it and you will often hear the omniscient style referred to as "head-hopping." Don't get me wrong, there are a lot of great writers who write omnisciently. (Agatha Christie's Murder on the Orient Express is an example.)
Puristic point of view, however, allows your readers to more intimately relate to your characters. It allows you as the author to show your readers what your characters are thinking and feeling, as well as what they are doing. It could be argued that omniscient POV does this too, but the advantage that puristic POV gives is that it allows you to do this in a way that your reader can easily follow. When reading omniscient it always takes a moment for the reader to realize they are seeing the scene through a different character's eyes and then begin to make a connection with that character. Puristic POV eliminates that delay.
There are two things to remember when trying to write a good puristic POV story.
For puristic POV to work, the author can only state things that can be KNOWN by the character whose perspective they are in. So for example, if Suzy is your POV character and she has her back to John, another character, you cannot tell us, "John bent and unlaced his shoes," because Suzy can't SEE that happening. You can however write something like, "John's knees popped as he squatted down. A moment later the soft thud of his shoes hitting the floor and the squeak of the bedsprings told her he'd called it a night." All those sounds are things she could hear and then infer his actions from, so that still keeps us in her POV.
Puristic POV can have more than one POV character, however there should be a hard break between sections written from different points of view. So, if we keep with our above example, and after John climbs into bed we want to let the reader know what John is thinking, we could do something like this:
John curled his arm under his head and suppressed a groan at the thought of the alarm going off at 5am. He hoped Suzy would be quiet when she crawled in. Then again, Gabriel's trumpet itself probably wouldn't be able to wake him tonight."
The reader immediately knows they are in John's POV because they are being told things that Suzy could not know. The hard break makes this transition easy and smooth.
I know I've only touched on POV here, so do you have any questions for me? I'll be happy to try and help you understand anything that isn't quite gelling yet!