General upper secondary education continues the teaching and educational tasks of basic education to students aged about 16–19. Upper secondary school takes normally 3 years. The general upper secondary school ends in the matriculation examination which gives eligibility for all higher education studies.
At an upper secondary school all the students have to take specific obligatory courses. In addition, students may choose extra courses. To get an upper secondary school diploma, everyone has to have at least 75 courses, but they can take more courses if they wish.
For further information on Finnish upper secondary schools, see the following

https://minedu.fi/en/general-upper-secondary-education