Service means a lot of things. In my opinion I believe that service means to help people or assist people in need of help. Like if someone needs the door open you can help them out by opening it for them
Service in A-5 - If someone gets hit by a ball and is hurt you can ask them if they are okay and see if they need help to get up. If someone is new you can explain them the rules or help them out by showing them the ropes on how to play. Doing something small can inspire someone to help others in need and it will go around.