This is the 10144th most frequent Russian word.
бейсболка
A baseball cap.
The word 'бейсболка' is used as a direct object in the sentence to indicate the item purchased, emphasizing its role as a common noun for a type of hat.
Я купил себе новую бейсболку.
I bought a new baseball cap for myself.
Here, 'бейсболка' refers to a specific item (the speaker's worn-out cap) used as the subject of the need for replacement.
Моя старая бейсболка износилась и требует замены.
My old baseball cap is worn out and needs replacement.
In this example, 'бейсболка' is part of the action in the sentence (wearing) and demonstrates utility for protection.