This is the 8471st most frequent Russian word.
неделю
"Неделю" means "week" in English.
Here, "неделю" is used in the accusative case to indicate the duration of time.
Я жил у бабушки неделю.
I stayed at my grandmother's for a week.
"Неделю" is in the accusative case, indicating the time period after which the action will occur.
Они обещали закончить ремонт через неделю.
They promised to finish the repairs in a week.
The sentence shows a related form "неделе" in the prepositional case, referring to the time of the action.