This is the 127th most frequent Icelandic word.
þeir
"They" (masculine plural).
The word "þeir" refers to a group of people, specifically males or a mixed-gender group.
Þeir eru að fara í bíó.
They are going to the cinema.
The pronoun "þeir" refers to the individuals being inquired about, emphasizing location.
Veistu hvar þeir eru núna?
Do you know where they are now?
Here, "þeir" is the subject pronoun for a group that completed an action together, indicating they.