Behind hedges too tall to see over, the ones in white are playing tennis.
They play well. The rallies are long, the clay is swept between sets, and water arrives without anyone asking for it. Shown only this, you would call it a good afternoon at a good club.
The ones in navy are not playing anything. They stand at the edges where the shade is. They watch, and they do not appear to be waiting for a turn.
Nobody asks what they are for. That is the first rule here, and it is not written down anywhere, which is how you know it is the important one.
The score is being kept somewhere none of the players can see.