If it is in the UK then they would have just completd year 12 and 13 and come out with their AS/A Levels. British education is higher than American schooling so we don't give out High School Diplomas, but children take exams in their specialist subjects readying them for their University Degrees. If your child is due to attend an American Univeristy then they may have to sit a High School equilvancy exam, but their is a service on-line which you can send their certificates to and they will translate them into American equilavents.