This is the 11100th most frequent Russian word.
голубым
"Golubym" means "light blue" or "sky blue" in English.
In this sentence, "голубым" is used as an adjective in the instrumental case describing the color of the eyes.
У него были голубым цветом глаза.
He had blue-colored eyes.
Here, "голубым" acts as an adjective in the instrumental case describing the sky.
Голубым небом веяло спокойствие.
The blue sky exuded calmness.
In this sentence, "голубым" is used as an adjective in the instrumental case, specifying the quality of the material.