What does the largest number on the Heroes of the Storm scoreboard indicate?
Solution 1:
It's the number of hero takedowns your team had over the game.
In this example, my team killed the enemy team 20 times.
Note this won't be a perfect sum of the takedown columns for each team. That's because each hero gets credit for a takedown if they were in the area or did damage to that hero within a short time of that hero's death.