This is the 126th most frequent Persian word.
اند
The Persian word "اند" is a verb suffix meaning "are" or "they are" in third-person plural.
The word 'اند' here is used as a verb to indicate the plural third-person present tense of 'to be'.
آنها دانشآموزان کوشاییاند.
They are diligent students.
In this sentence, 'اند' is part of a compound past perfect verb and is used as the third-person plural auxiliary verb 'have'.
استادان جدیدی برای دانشگاه انتخاب شدهاند.
New professors have been chosen for the university.
Here, 'اند' functions as part of the present perfect tense, combining with 'نکرده' to mean 'haven't' in the third-person plural.