This is the 2652nd most frequent Polish word.
babci
"Babci" means "grandmother's" in English.
Here, 'babci' is the genitive case of 'babcia', used after the preposition 'do', indicating direction towards.
Idę do babci na obiad.
I am going to grandma's for lunch.
In this sentence, 'babci' is the locative case of 'babcia', used with the preposition 'u', indicating a location.
Spędziłam weekend u babci.
I spent the weekend at grandma's.
The word 'babci' is in the genitive case, used here with the preposition 'od', indicating possession or origin.