This is the 624th most frequent Korean word.
높게
"Highly" or "tallly."
Here, '높게' is describing the height of the mountain peak relative to the sky, indicating vertical elevation.
산 정상은 하늘 높게 솟아 있다.
The mountain peak soars high into the sky.
Here, '높게' is used to describe the pitch of the singer's voice as perceived by the listener.
그 가수의 소리는 매우 높게 들린다.
The singer's voice sounds very high.
In this sentence, '높게' describes the altitude at which the bird is flying.