This is the 4036th most frequent Russian word.
малой
"Maloy" means "little one," "kid," or "youngster" in informal Russian.
In this sentence, 'малой' is used informally to refer to a younger person, typically a child or someone younger than the speaker.
Малой, помоги мне перенести коробки.
Hey, kiddo, help me carry the boxes.
Here, 'малой' is an adjective describing the size of the kitten, meaning 'small' or 'young'.
Я заметил, что малой котёнок играет с нитками.
I noticed that the small kitten is playing with strings.
In this example, 'малой' modifies 'дуб', indicating the oak tree is small or young.