This is the 8th most frequent Icelandic word.
hefur
"Has" or "have" (present tense of the verb "to have").
In this sentence, 'hefur' is part of a present perfect verb phrase indicating a past action relevant to the present.
Þetta hefur gerst áður.
This has happened before.
The word 'hefur' is used here to signify possession or ownership.
Hún hefur marga vini.
She has many friends.
The word 'hefur' indicates the present perfect tense, combining the auxiliary verb and main verb to indicate an action that is completed in the present.