See here for an example: https://www.youtube.com/watch?v=XAq-xp54j1w
The play gets repeated a couple of times and explained in some detail throughout but you can see what happens in the first few seconds of the video - blue is about to receive the ball in an incredibly advantageous position (a couple of steps away from scoring) white performs a deliberate foul in defending that play (they deliberately knock it forward and out of play, without trying to catch it). There's more to it than just "a very egregious foul against an attacker" but it's a good-enough simplification for our purposes.
People are already quite resistant to VAR in football already (got my own opinions on that) so I think there's virtually zero chance of football adopting this. But if ever there was an argument for it, it's definitely that Suarez case in 2010, Ghana were cheated out of an historic World Cup semifinal appearance.