You should start by understanding what break even actually means. It’s essentially the point where you are making neither a loss nor a profit. It’s the point onwards where your investment is worthwhile. It’s the point where your revenue equals your expenses (fixed costs, variable costs and the cost of the investment).
The break even analysis is used to find how many units you need to sell to make a profit (if the price is fixed or almost fixed) or how much should you sell for to be able to make a profit or at least not a loss.