Does being a school prefect help in university admission?

Positions of responsibility help somewhat in the admissions evaluation.

Sports are always good.

Extracurricular activities that support your proposed major are very strong enhancements. EG: If you are a science or math major, then secondary school activities in science and math related activities are great enhancements. Also, our math professors maintain that musical activities are enhancements -

Fluency in another language - not the informal street-talk at home and with friends, but highly grammatical and literate written and spoken language.