This is the 124th most frequent Persian word.
باشند
"باشند" means "they are" in English.
In this sentence, 'باشند' functions as the third-person plural form of the subjunctive verb 'to be', expressing a condition or state that is desired or required.
آنان باید با دقت عمل کنند که کارهایشان درست باشند.
They must act carefully so that their work is correct.
Here, 'باشند' is used in a subjunctive mood following the verb expressing desire, indicating a state that is hoped for.
ما میخواهیم که دوستانمان خوشحال باشند.
We want our friends to be happy.
In this context, 'باشند' is part of a possibility statement, implying the books' potential usefulness.