This is the 2218th most frequent Russian word.
действуют
"Act" or "operate."
Here, 'действуют' refers to the action or effect the medicines have on the body.
Лекарства действуют быстро и эффективно.
The medicines act quickly and effectively.
In this sentence, 'действуют' describes the actions politicians take related to public welfare.
Политики действуют в интересах общества.
Politicians act in the interest of the society.
Here, 'действуют' is used to indicate the operation or functioning of machines.