The United States is a country of small and large businesses, so it helps to know how to talk about this subject. Here are things you’ll hear people say:
Someone is opening a new business.
They’re starting a business.
He wants to get into business.
He wants to be a business man.
She has her own business.
She’s a business woman.*
Let’s do business.
What kind of business are you in?
Are they open for business yet?
It looks like that place is going out of business.
They lost their business.
That business failed.
There are many idioms and expressions that use the word "business."
There will be no more monkey business. (Stop playing around.)
That’s none of your business. (This situation does not concern you–stay out of it.)
Mind your own business. (same as above)
They have no business doing that. (They shouldn’t be doing that.)
Where’s the business end of the machine? (Where’s the part of the machine that does the work?)
Everything is business as usual. (Nothing has changed, or everything is back to normal.)
This is strictly business. (This situation does not involve personal matters.)
Let’s get down to business. (Let’s do our work, or let’s now talk about serious matters.)
That’s show biz. (That’s the way things go. The word "biz" is short for "business.")
He’s a business man.
*Note: It’s also common to hear a man or a woman in business described as a business person.
He’s a business man.