This is the 15304th most frequent Russian word.
постели
"Beds" or "bedding."
In this sentence, 'постели' refers to the beds or bedding that were used by the guests.
Он убрал постели после гостей.
He cleaned up the beds after the guests.
Here, 'постель' is used in singular form to refer to the act of arranging the bedding.
Каждый день она заправляет постель.
Every day she makes the bed.
In this sentence, 'постели' is part of the verb form meaning 'to lay out the bedding or cover.'