This is the 772nd most frequent Czech word.
rodinu
The Czech word "rodinu" means "family" (in the accusative singular form).
Here, 'rodinu' serves as the direct object of the verb 'navštívili jsme', referring to the family being visited.
Navštívili jsme rodinu na venkově.
We visited the family in the countryside.
In this sentence, 's rodinu' means 'with the family', where 'rodinu' is in the accusative case governed by the preposition 's' which necessitates the accusative form.
Plánuji s rodinu strávit letní prázdniny.
I plan to spend summer holidays with the family.
Here, 's celou rodinu' highlights the inclusion of 'celou' (whole), placing 'rodinu' in the accusative case to match its grammatical role and agreement.