축하해 (casual) · 축하해요 (polite) · 축하드립니다 (formal)
congratulations (formal, respectful)
Example
두 분의 결혼을 진심으로 축하드립니다.
Sincere congratulations to you both on your wedding.
Word parts
축 celebrate+하 congratulate
축하 'celebrate and congratulate' plus humble 드리다 'give'.
Good to know
Pronounced [추카드림니다] — ㄱ+ㅎ becomes ㅋ, and ㅂ before ㄴ becomes ㅁ.
Related words