This is the 524th most frequent Korean word.
건강
Health.
The word '건강' is used as a noun to indicate the state of being healthy, serving as the subject of the sentence.
건강이 정말 중요합니다.
Health is really important.
In this sentence, '건강' represents a concept for a goal or reason (reason for adopting a balanced diet); it is commonly used in such explanatory contexts.
건강을 위해서는 균형 잡힌 식사가 필요합니다.
For health, a balanced diet is necessary.
'건강' is used here as a noun, representing a condition to be preserved, and serves as the object of the verb '유지하다' (to maintain).