This is the 783rd most frequent Catalan word.
hauran
"Hauran" is the third person plural future form of the verb "haver," meaning "they will have" in English.
The word 'hauran' is used here to form the future tense of the verb 'haver' indicating necessity when combined with 'de'.
Demà hauran d'arribar abans de les deu.
Tomorrow they will have to arrive before ten.
In this instance, 'hauran' is used to express probability in the future perfect, suggesting something that might have happened by the time of speaking.
Els amics hauran sortit a passejar.
The friends will have gone out for a walk.
The verb 'hauran' in this sentence is functioning as part of the future perfect tense, indicating an action that will be completed before another future event.