All schools have a behaviour policy that sets out how pupils are expected to behave in the classroom, during break times and outside school (e.g. at bus stops). You should be able to download this from the school’s website, or ask for a copy from your child’s teacher.
If your child does not follow the behaviour policy, they could get detention, be temporarily excluded, or as a last resort, be permanently excluded from the school. Your child’s school will be able to provide guidance on exclusion from schools.