This is the 2884th most frequent Russian word.
бутылку
"Бутылку" is the accusative form of "бутылка," meaning "bottle" in English.
The word 'бутылку' is in the accusative case, indicating the direct object of the verb 'bought'.
Я купил бутылку воды.
I bought a bottle of water.
The word 'бутылка' is in the nominative case, serving as the subject of the sentence.
На столе лежит бутылка.
A bottle is lying on the table.
The word 'бутылки' is the plural accusative form, representing multiple items as the objects being acted upon.