Complex sentence: Concurrent enrolment (BE) or concurrent enrollment (AE) is the process in which high school students enroll at a university or college to attain class credit for high school and/or college.
Split into simpler sentences: Concurrent enrolment (BE) or concurrent enrollment (AE) is a program through which students earn college credit for courses taken during high school. Students enroll at a university or college to attain class credit for high school and/or college.