This is the 31st most frequent Bulgarian word.
бъдат
"Бъдат" means "be" (third person plural, future tense).
Here, 'бъдат' is used in the future tense to indicate a state of being—a prediction about their presence at the meeting.
Те ще бъдат на срещата утре.
They will be at the meeting tomorrow.
In this sentence, 'бъдат' is used as a subjunctive mood verb, expressing a wish or order for their state of being.
Нека бъдат подготвени за следващия изпит.
Let them be prepared for the next exam.
Here, 'бъдат' is part of a passive construction, showing how an action affects them underlying their state of being.