Level 1 is a basic course in boat handling and launching/ Recovery (although they do not get involved with the launching and just watch if they are 8) At 8 you get an endorsed certificate until they are 16, basically they have to go out with an adult and are not technically allowed out using their licence on their own until they are 16.
Ideally, when your child is 16 he can do the powerboat level 2 straight off and get the licence if successful without any endorsements and bypassing level 1. Hopefully that helps a bit