Margin (emphasis on the second "a") is an economic term, in the broadest sense, meaning the difference between the cost price and the selling (selling) price of any product or asset. Most often, the margin is expressed as a percentage for convenience of comparison. If, for example, the store buys vodka at 100 rubles per bottle, and sells 150, then the margin for such vodka is 50%.
The English word "margin" is usually translated as "edge, limit" . It goes back to the French "marge", which can also mean "difference" or "advantage".
Example of use:
In the sale of air tickets, the margin is usually very low, so you need a lot of turnover.