This is the 17316th most frequent Russian word.
сыновей
"Сыновей" means "of sons" or "sons'" (genitive plural in Russian).
The word 'сыновьями' is the instrumental plural form of 'сыновья' (sons), indicating the means or companionship in the sentence.
Он гордится своими сыновьями.
He is proud of his sons.
The word 'сыновей' is the accusative plural form of 'сыновья' (sons), used as the direct object of the sentence.
Я видел сыновей у школы.
I saw the sons near the school.
The word 'сыновьях' is the prepositional plural form of 'сыновья' (sons), used after the preposition 'о' to indicate the topic of conversation.