Enrollment/taking a course — registering for and attending classes (often in school/university) to earn credits.
来学期は経済学の入門科目を履修する予定だ。
Next semester I plan to take an introductory economics course.
履修要件を満たすには必修科目を含めて最低30単位が必要だ。
To meet the course requirements you need at least 30 credits, including required courses.
履修登録は今週で締め切りなので、忘れずに申請してください。
Course registration closes this week, so don't forget to apply.