This is the 11190th most frequent Korean word.
기운
Energy; strength; spirit; mood.
In this instance, '기운' refers to someone's apparent vigor or liveliness.
오늘은 기운이 없어 보여요.
You seem to lack energy today.
In this sentence, '기운' refers to the general atmosphere or feeling of positivity.
기운이 좋으면 일이 술술 풀린다.
If the energy is good, things go smoothly.
Here, '기운' is used to denote one's physical stamina or vitality.