This is the 1187th most frequent Russian word.
девушку
"Девушку" means "girl" or "young woman" in the accusative case.
Here, 'девушку' is in the accusative case, functioning as the direct object of the verb 'вижу' (I see).
Я вижу девушку у фонтана.
I see a girl by the fountain.
In this sentence, 'девушке' is in the dative case, indicating the indirect object receiving the flowers.
Мужчина подарил девушке цветы.
The man gave flowers to the girl.
Here, 'девушкой' appears in the instrumental case, used to denote the means or accompaniment in the action described.