This is the 580th most frequent Icelandic word.
lögreglu
"Police."
In this sentence, 'lögreglu' is used in its accusative form as the direct object of the verb 'hef samband við' (contact).
Ég hef samband við lögreglu ef það er neyðartilvik.
I contact the police if there is an emergency.
Here, 'lögreglunni' is in the dative form with the definite article, as governed by the preposition 'að' (to).
Það er mikilvægt að treysta lögreglunni.
It is important to trust the police.
In this sentence, 'Lögreglan' is the subject of the sentence in the nominative form with the definite article.