POV stands for ‘point of view’. It is your imaginary vantage point. It’s where your imaginary camera is located, although it is a special camera that records smells, sensations, and sometimes people’s thoughts, as well as sight and sound.
POV is your vantage point.
Grammar gives you clues to the POV. If you are in first person (I walked) then you know your POV is inside that character’s head. However, it is not the grammar itself that creates this effect, it is what information your camera is picking up. You can convert a passage written in first person to third person (he walked) by changing the grammar and it still feels like you are in the person’s head. So, despite what you were told in high school, POV is not just a matter of whether you use “I” or “she”, but rather recreating a particular vantage point from which you are telling the story.
FYI, second person (you walked) does exist but is rarely used. If you are writing third person, you have various options.
You can write from inside the character’s head, which mimics first person just with slightly different grammar. You can write from just over the character’s shoulder (you see what they see but not their internal thoughts). You can write from over the character’s shoulder and occasionally dip into first person with or without some kind of formatting clue like italics. You can write like an intelligent fly on the wall, observing events but from no particular character’s perspective. Or you can be fully omniscient, popping in and out of characters’ heads at random.
You can also have a particular POV not just in place but in time. For example, you can write a fictional ‘memoir’, looking back and telling us what happened. (‘When I was a child, I used to catch the bus.) Alternatively, you can position yourself in character’s present, experiencing events unfold without foreknowledge (‘I swing my schoolbag onto my shoulders and climb the steps of the bus.’). Often this will be indicated by tense, but not necessarily. You can write in past tense but limit your observations only to the present moment, thereby having a present-day POV despite the tense. (‘I swung my schoolbag onto my shoulders and climbed the steps of the bus.’)
Whatever POV you choose, it is generally a good idea to be consistent, otherwise the reader will find it jarring, and it may look like you don’t know what you’re doing. You will also find that some readers are a bit fascist about POV and believe there are hard and fast rules that you cannot head-hop, and cannot slip in omniscient observations if you are in close third person.
This is not true.
There is no ‘rule’ against head-hopping, just as there never really was a rule against splitting infinitives. However, there are conventions and expectations. In many kinds of fiction, head-hopping is not in fashion and you will piss many people off if you do it. But more than that, it is hard to do head-hopping well, and if done poorly it is hard to follow, dilutes the sense of each character’s personality and perspective, and suffers from association with being a ‘rookie mistake’ that new writers make when they don’t know what they’re doing or can’t think of a more clever way to show how a non-POV character is reacting.
So, if that’s POV, what is voice?
Voice is the personality of the writing, expressed through the style of the language and the opinions of the narrator.
A narrator who begins: ‘I stared at the casket with the dull knowledge that I should probably feel something, but feelings had gone away.’ has a very different voice to the narrator who begins: ‘I love a good funeral .’
Even when a specific character doesn’t narrate, a sense of voice comes across through what is and is not observed. Is this a voice that notices the tragic beauty of a sunset, or one who jogs on to make sure they are home for the 6.30 news while neurotically wondering whether everyone she passes thinks her outfit is too frumpy, or one that immediately assesses the five best locations for a sniper?
Voice can also be expressed through stylistic choices. Is the writing clipped and controlled or do the thoughts jumble into one another? What does the vocabulary and sentence structure tell us about the narrator’s education and knowledge of the world? Is the voice a ‘written voice’, carefully composed, or does it have the spontaneity and immediacy of speech or thought. You can write some or all of a novel in emails or letters, or even text messages, and these choices lead to adopting different voices.
For a discussion of how POV and voice are used in fantasy, I have posts on: