I notice that at the end of a "Heroes of the Storm" match, 5 players are picked. The MVP of the game, and 4 others that had major contributions to the game. There is a little up-arrow icon under each character, that you can press to give them a point. I've played some games where one person gets all 5 points, and seen games where everyone gets a single point. Do these points have any effects on the overall game (increase experience points awarded, increase money awarded, etc)?
No, not at all. They are just a way to show appreciation towards a player you felt performed very well.
Specifically here you can see the blog post where Blizzard introduced it, and under "Commending a contender," they describe it as a virtual "thumbs-up".