Learn Croatian: Idem u mesnicu po svježe meso. - I am going to the butcher shop for fresh meat.

When you go somewhere specifically to fetch, collect, or pick something up, Croatian uses the preposition po followed by the accusative case. Using za here is a very common mistake for English speakers, but it sounds unnatural in Croatian. You use po because you are going to the butcher specifically to bring meat back with you.

What case is svježe meso in after po?

It is in the accusative case. The preposition po requires the accusative when it means "to get" or "to fetch". Because meso is a neuter noun, its accusative form is identical to its nominative (dictionary) form, and the adjective svježe (fresh) matches this neuter accusative form.

Why do we use u mesnicu instead of the locative form u mesnici?

Because the verb ići (conjugated here as idem) indicates motion towards a destination. When the preposition u shows direction or destination, it requires the accusative case, which makes the feminine noun end in -u (mesnicu). If you were already inside the shop, you would use the locative case, for example: Kupujem meso u mesnici (I am buying meat in the butcher shop).

Is the -nica ending in mesnica a common pattern for naming shops?