Word Network: 퇴직하다

Retirement; the action of leaving one's job.

Severance pay; money paid upon termination of employment.

Retirement age; the age at which one stops working permanently.

A formal letter or document used to resign from one's employment.

Changing one's job or moving to a different company. This is a common theme in IELTS General Task 1 (letters) and Task 2.