"The chairs of the house"
Translation:Viti vya nyumbani
Nyumba means house. When you are saying 'at the house/in the house/of the house...etc' ,nyumba takes on the locative case which adds 'ni' to the end of it turning it into 'nyumbani'. Same thing for other places for example 'mkutano-meeting'. Ninaenda mkutanoni - im going to a meeting. See how it gained 'ni' at the end.