mean business
US /miːn ˈbɪz.nɪs/
UK /miːn ˈbɪz.nɪs/

1.
是认真的, 不是开玩笑的
to be serious and determined about what one is doing or saying
:
•
When the boss walked in with that look on his face, we knew he meant business.
当老板带着那种表情走进来时,我们知道他是认真的。
•
The new security measures show that the company means business about protecting its data.
新的安全措施表明公司是认真的,要保护其数据。