Questions & Answers about U selu žive moja baka i moj deda.
Because u can take two different cases depending on meaning:
- u + locative = in/at a place, when there is no movement
- u + accusative = into/to a place, when there is movement toward it
Here, the sentence describes where the grandparents live, so it uses location, not motion:
- u selu = in the village
Compare:
- Žive u selu. = They live in the village.
- Idem u selo. = I am going to the village.
So selu is the locative singular of selo.
Selu is in the locative singular.
The noun is:
- nominative: selo = village
- locative: selu = in the village / at the village
It appears in the locative here because it follows u in a location meaning.