This is the 628th most frequent Korean word.
되어
"되어" means "become" or "is done" depending on context.
In this sentence, '되어' is used to indicate becoming something (a doctor in this case).
그녀는 의사가 되어 많은 사람들을 도왔다.
She became a doctor and helped many people.
Here, '되어' implies the state of being scheduled or arranged.
내일 회의가 오후 3시에 되어 있습니다.
Tomorrow's meeting is set for 3 PM.
In this context, '되어' represents the act of transforming into or becoming (a dream into reality).