There are 4 people who are all playing badminton and the boy in the white shirt is the first one to serve to the man in the black shirt.  Then the man wearing the black shirt serves to the boy whose wearing the gold shirt.  Then the boy who's wearing the white shirt hits the shuttlecock and serves to the girl who's wearing the pink shirt and the game goes on and everyone keeps serving to each other and they all use different shuttlecocks.