This is the 5987th most frequent Russian word.
скажут
"They will say."
The word 'скажут' is a future tense, third-person plural form of the verb 'сказать', used here to indicate that a group of people will tell or convey information.
Они скажут тебе всю правду.
They will tell you the whole truth.
In this sentence, 'скажут' conveys the action of expressing an opinion or thought, also in the future tense.
Люди, наверное, скажут, что это невозможно.
People will probably say that this is impossible.
Here, 'скажут' is used in a conditional future statement, illustrating the timing of the communication.