This is the 10008th most frequent Russian word.
арестуют
"Арестуют" means "will arrest."
In this sentence, the word 'арестуют' is used in the future tense to indicate a possible outcome.
Если человек нарушит закон, его арестуют.
If a person breaks the law, they will be arrested.
Here, 'арестуют' again serves as a future tense verb, showing action taken under set conditions.
За протест против несправедливости людей арестуют.
For protesting against injustice, people are arrested.
In this example, 'арестуют' refers to a potential future action that was advised in advance.