If you break even on an investment, sale, etc., you neither have a profit nor a loss.
投資や売上において、break even と言うと、利益も損失もない、つまり、損得なしになる、という意味です。
Examples
Altogether, it’s going to cost us about $50,000 to organize and promote the event. That means we’ll have to sell 5000 tickets at $10 each just to break even.
I don’t expect to make any money with the Web site; it’s more of a hobby than a business. I just hope I can break even.
a: How’s the business going? Back on your feet yet? b: Not really. We’re still barely breaking even.