This is the 5976th most frequent Russian word.
сестра
Sister.
The word 'сестра' here is used in a familial context to refer to one's biological (or adopted) sister.
Моя сестра любит читать книги.
My sister likes to read books.
The word 'сестра' in Russian can also colloquially refer to a nurse, emphasizing a sense of caregiving and professional context.
Вчера я встретил сестру из больницы.
Yesterday, I met a nurse from the hospital.
In casual speech, 'сестра' can address someone affectionately or familiarly, reflecting camaraderie or friendship.