The first number you say is the serving team’s score. The second number you say is the receiving team’s score. The third thing you say is “1” (when it’s the first person serving on your team) or “2” (when it’s second person serving on your team).
For example, if the serving team was up 5-3 and on the first serve, the person serving would say “5-3-1,” then serve. You continue to alternate serve sides until a fault, then it goes to the other player.
If you are playing singles, you only have to say the serving person’s score and the receiving person’s score.