Breakdown of Lestarstöðin er á þessari götu, hjá bankanum.
vera
to be
á
onto / on / in (static location) / on (a day of the week)
hjá
next to / at (someone's) place, with
þessi
this (m/f)
Questions & Answers about Lestarstöðin er á þessari götu, hjá bankanum.
Why is it þessari instead of þessi?
Þessari is the dative feminine singular form of þessi ("this"). The preposition á requires the dative case here because it describes a fixed location. Since the word for street (gata) is feminine, the word for "this" must match it in gender, number, and case, so it becomes þessari.
Why did gata (street) change to götu?
Gata is a weak feminine noun, which means its ending changes from -a to -u whenever it is not in the nominative subject case. Because it comes after the preposition á in a way that indicates location, it is in the dative case here, taking the -u ending and causing the first vowel to shift to ö.
Does the preposition á always trigger the dative case?
No, á is a two-way preposition. It takes the dative case when describing a fixed location or state (like a station sitting "on" a street). If you were describing movement or a change of location (like stepping onto the street), á would take the accusative case instead.
Why does the word for "the bank" end in -num here?