Английский словарь американских идиом - mean business

{v. phr.}, {informal} To decide strongly to do what you plan to do; really mean it; be serious. * /The boss said he would fire us if we didn't work harder and he means business./ * /When she went to college to study, she meant business./ * /He just liked the company of the other girls he dated, but this time he seems to mean business./