This is the 3566th most frequent Russian word.
сестры
"Sisters."
Here, 'сестры' is used as the plural form of 'сестра' (sister) in the nominative case.
Сестры играют в парке.
The sisters are playing in the park.
In this sentence, 'сестры' is in the dative case (plural form), showing the indirect object of the verb 'пошли' (went).
Мы пошли в гости к сестрам.
We visited the sisters.
Here, 'сестры' is in the dative case (plural form), functioning as the indirect object receiving the gift.