This is the 11637th most frequent Korean word.
날아가는
"날아가는" means "flying" or "flying away."
The term '나는' here denotes the act of flying by the bird as an adjective modifying the noun 'bird.'
하늘을 나는 새를 보세요.
Look at the bird flying in the sky.
The phrase '날아가는' describes the continuous action or state of flying associated with the paper airplane.
종이비행기는 멋지게 날아가는 것이 보입니다.
You can see the paper airplane flying beautifully.
In this sentence, '날아가는' illustrates the motion of the balloon carried away by the wind.