This is the 5967th most frequent Russian word.
секунду
"Секунду" means "a second" (a brief moment of time).
In this sentence, 'секунду' is used to indicate a very short amount of time, typically implying the speaker will return very quickly.
Подожди секунду, я сейчас вернусь.
Wait a second, I'll be right back.
Here, 'секунду' is used to emphasize brevity in duration, highlighting how quickly the action was completed.
Это заняло всего секунду, и я сделал всё.
It only took a second, and I accomplished everything.
In this case, 'секунду' is used to describe a precise moment in time, giving focus to the singular instance of the action.