Johannesburg South High school (North America) (usually grades 9–12 but sometimes 10–12, it is also called senior high school) is always considered secondary education; junior high school or intermediate school or middle school (6–8, 7–8, 6–9, 7–9, or other variations) are sometimes considered secondary education.
Higher education is any school you go to after Johannesburg South high school. You might go to a college or university. You might go to a community college. You might go to a career school.