Breakdown of Þau fagna brúðkaupsafmælinu sínu í maí.
þau
they (n)
í
in / into / to (before the hour, in telling time) / per (in frequency expressions)
sinn
his/her/their own (sinn, sína, sitt)
maí
May
Questions & Answers about Þau fagna brúðkaupsafmælinu sínu í maí.
How do we say that an event happens in a specific month?
To say something happens in a certain month, you use the preposition í followed by the name of the month. Month names in Icelandic do not change their endings in this context. So in May is simply í maí, just like in January would be í janúar.
Why is the word for wedding anniversary in the dative case here?
The verb fagna (to celebrate or to welcome) always forces its object into the dative case. That is why we must use the dative form brúðkaupsafmælinu instead of the accusative.
Why do we use sínu for their instead of þeirra?
How is the long word brúðkaupsafmælinu put together?
It is a compound word made of brúðkaup (wedding) and afmæli (anniversary or birthday), joined by an s. The -nu at the very end is the attached definite article (meaning the), shaped for a neuter dative noun.