Learn Farsi: ایشان استادند. - They are professors. formal

Both mean "they", but ishân is specifically used for people and carries a tone of formal respect. ânhâ is the standard, everyday word for "they" and can refer to people, animals, or objects.

The English translation says "professors", but ostâd doesn't have a plural ending. Why is that?

In Farsi, when you use a plural subject like ishân and a plural verb ending like -and, the noun describing them usually stays in the singular form. The plurality is already clear from the pronoun and the verb, so you do not need to add a plural ending to make it ostâdhâ.

Where is the word for "are" in this sentence?

It is the suffix -and attached to the end of ostâd. This is the third-person plural form of the "to be" verb. Instead of standing alone, it attaches directly to the noun, making ostâdand (literally "professor-are").

Could this exact same sentence mean "He/She is a professor"?

Yes, absolutely! In Farsi, you can use the plural pronoun ishân and the plural verb ending -and to talk about a single person as a sign of respect. Depending on the context, this sentence could translate to "He is a professor" or "She is a professor" when speaking formally.