The "profit margin" for a business is the amount of money that the business keeps after paying its expenses.

For example, a grocery store might buy a box of cookies for $1.00 and sell it for $2.00. In that case, the "profit margin" is 50%.

Here are a few phrases that people use when talking about "profit margins":

Our profit margins are slim.

They have huge profit margins.

You have to have a healthy profit margin.