This is the 11890th most frequent Korean word.
네모
Square.
Here, '네모난' describes the shape of the 'box', specifying it as square in shape.
네모난 상자는 저기에 있습니다.
The square box is over there.
In this sentence, '네모' is a noun referring to the shape 'square'.
그가 네모를 그렸습니다.
He drew a square.
In this case, '네모' is used as a plural noun to indicate multiple square shapes present in the picture.