This is the 1280th most frequent Spanish word.
hermanos
"Brothers" or "siblings."
In this sentence, 'hermanos' is used to refer to siblings in general, which can include both brothers and sisters.
Mis hermanos son muy simpáticos.
My siblings are very nice.
Here, 'hermanos' indicates that Juan and María are siblings, again without specifying their gender.
Juan y María son hermanos.
Juan and María are siblings.
In this context, 'hermanos' specifically refers to the speaker's older brothers, indicating a gendered use of the word.