Learn Icelandic: Getur þú sagt mér hvar stoppistöðin í miðbænum er? - Can you tell me where the stop in the city center is?

In a direct question, the verb comes right after the question word: Hvar er stoppistöðin? (Where is the stop?). But in an indirect question like we have here, the word order changes to Subject + Verb, just like in English: ... hvar stoppistöðin ... er (... where the stop ... is).

Why do we use the dative mér instead of the accusative mig here?

The verb segja (to say/tell) takes a dative object for the person receiving the information. Because of this, "tell me" is always segja mér.

Why is the verb sagt used after getur þú instead of the infinitive segja?

The verb geta (can/to be able to) is a bit special in Icelandic. Instead of taking an infinitive verb like most helper verbs do, it always requires the following verb to be in the supine form (which looks exactly like the neuter past participle). That is why we use sagt instead of segja.

Why is miðbænum in the dative case?

The preposition í takes the dative case when it describes a fixed location (where something is), rather than movement towards a place. Since the bus stop is located in the city center, miðbær (city center) gets the dative definite ending -num.