This is the 5993rd most frequent Polish word.
śpią
"Śpią" means "they sleep" in English.
In this sentence, 'śpią' is used in the indicative form to describe a present, ongoing action of sleeping by the children.
Dzieci śpią spokojnie w swoich łóżkach.
The children are sleeping peacefully in their beds.
Here, 'śpią' is employed in an interrogative sentence form asking about the current state of sleeping of the subjects.
Czy oni śpią teraz?
Are they sleeping now?
In this example, 'śpią' is used in a subordinate clause to refer generally to the act of sleeping, indicative of a habitual occurrence.