You will need a good pair of soccer cleats for games and practices.
While the team will provide balls for practice, it would still be a good idea to have a ball to use outside of practice. Many drills to improve ball skills and shooting can be completed outside of practice.
Players need to have shorts and t-shirt each day for practice. Shin guards are required for games and it would be good to get used to them in practices.
Each player needs their own water bottle to use for practices and games. Individual water bottles help reduce the sharing of germs and illness.