This is the 8240th most frequent Russian word.
мальчик
Boy.
Used here to identify a young male child as the subject of the sentence.
Мальчик играет в парке.
The boy is playing in the park.
Used here to describe someone's male child with a complimentary characteristic.
Это мой сын, и он очень умный мальчик.
This is my son, and he is a very smart boy.
Used here in the accusative case to show the boy was receiving the action in the sentence.