This is the 4154th most frequent Russian word.
рустем
"Рустем" is a male given name of Persian origin, equivalent to "Rustam," meaning a legendary hero or warrior in Persian mythology.
Here, 'Рустем' is a proper noun, used as the name of a person to indicate the subject of the sentence.
Рустем любит играть в шахматы.
Rustem likes to play chess.
In this sentence, 'Рустема' is in the genitive case, showing possession or a relationship ('of Rustem').
Сегодня у Рустема день рождения.
Today is Rustem's birthday.
The word 'Рустема' is in the accusative case as it is the direct object of the action 'met'.