This is the 802nd most frequent Icelandic word.
hafnarfirði
"Hafnarfirði" means "in Hafnarfjörður," referring to a town in Iceland.
In this sentence, 'Hafnarfirði' is in the dative case, indicating a location where the action is taking place.
Ég bý í Hafnarfirði.
I live in Hafnarfjörður.
Here, 'Hafnarfjörð' is in the accusative case, showing motion towards or to the location.
Ég heimsótti Hafnarfjörð í sumar.
I visited Hafnarfjörður in the summer.
The word 'Hafnarfjörður' is in the nominative case, serving as the subject of the sentence.