Ok, there are more possible ways:
1. create object for every court - bad for customers which probably don't want to check every court if it is free in 20.3. 16:00, but with this they are able to select specific court. Many players can have their favorite courts.
There is also necessary to have sports as templates.
2. create object for every sport with capacity 5 - customers will only select sport and then book court. Specific court will be selected when customers will come to hall.
I am not sure if there is necessary to have sports as templates. It depends on situation.
You can have template court and objects tenis court and badminton court. One of property can be sport.