This is the 174th most frequent Croatian word.
nedjelju
"Nedjelju" means "Sunday" in English (accusative or locative case).
In this sentence, 'nedjelje' is in the genitive case, used here metaphorically as a possessive to mean 'of each Sunday' in the context of recurring events.
Svake nedjelje idem u crkvu.
Every Sunday I go to church.
In this sentence, 'nedjelju' is in the accusative case as it is specifying the time when the action 'to visit' will occur.
U nedjelju ćemo posjetiti baku.
On Sunday, we will visit grandma.
Here, 'Nedjelju' is also in the accusative case and is the direct object of the verb 'spend', indicating the day being spent.