How volleyball scoring works, on your wrist.
Rally point, set target, deciding set. The watch holds the set score so the bench does not have to shout it back after every side-out.
7, 15, 21, or 25
Indoor sets are usually first to 25, win by two, capped by the rules you play. Beach and short formats use 21, 15, or 7. Set the target once and every rally adds a point to the side that won it.
A shorter last set
The deciding set can use a different target from the sets before it, commonly 15, and the same win-by-two lead when you turn that on.
Same court, different count
Fistball uses the same set-and-point scoreboard: choose the points that win a set and how many sets win the match. It stays with volleyball here because both are team rally games, not a simple tap counter.
No phone in the rotation
Start the match on Apple Watch or Wear OS and leave the phone with the bags. Undo a disputed rally, then read the set score from the wrist between points.