This particle is added to nouns.
- ~로 is added to words ending in a vowel and also to those ending in ㄹ (for the ease of pronunciation).
- ~으로 is added to words ending in a consonant (except for ㄹ).
There are 7 ways you can use it:
- By means of, by, with
- To, toward
- Language
- A choice among many options
- To indicate transformation or change
- To express a cause or reason for a result
- To express the order in which something happened
1. By means of, by, with
- 저는 펜으로 서명했어요. / I signed with a pen.
- 학생은 학교에 자전거로 갔어요. / The student went to the school by bike.
- 저는 그 의자를 손으로 만들었어요. / I made that chair by hand.
2. To, toward
- 오른쪽으로 오세요. / Come towards the right side.
3. Language
- 저는 중국어로 말했어요. / I said it (or spoke) in Chinese.
4. A choice among many options (example: ice cream flavors)
Waiter: 무슨 맛으로 드릴까요? / What flavor would you like?
Guest: 딸기 맛으로 주세요. / Give me strawberry flavor please.
5. Transformation or change
- 비가 눈으로 변했어요. / The rain changed into snow.
- 탐이 부장님으로 고용됐어요. / Tom was hired as the manager.
- 혜란이가 예쁜 여자로 자랐어요. / Hyeran grew up to be a pretty woman.
6. To express the cause or reason for a result
- 김연아가 올림픽으로 유명해 졌어요. / Kim Yuna became famous because of the Olympics.
7. To express the order in which something happened.
- 저는 첫 번째로 먹을 거예요. / I will eat first.
Source: https://www.helloinkorean.com/discover-the-7-usages-of-%EC%9C%BC%EB%A1%9C-in-korean/