This is the 12779th most frequent Swedish word.
still
Calm, quiet, or motionless.
The word 'still' here is used as an adverb to mean motionlessness or being stationary, which is directly equivalent to 'still' in English.
Hon står helt still och lyssnar.
She stands completely still and listens.
The word 'still' here describes the calmness and lack of movement of the water, functioning as an adjective to convey the serene state.
Vattnet i sjön är så still att det ser ut som en spegel.
The water in the lake is so still that it looks like a mirror.
Here, 'still' is used to imply maintaining a stationary position or not moving, akin to the usage in English as an instruction or imperative.