A lady tells you how much an item is priced at Amazon and how much it costs from suppliers. Then she starts to calculate the profit. Then, she offers you to learn the success story from her.
I believe there are versions for each language. It's a shame that they only tell you to do the math comparing the selling price vs. the supplying cost. The problem is not the price difference but is how you can get the customer to make the purchase. Please don't fall into the trap because they will ask you to take classes to teach you all the nonsense. Eventually, you didn't learn that most of your cost is customer acquisition, where Facebook's primary revenue comes from!
Editor's Notes: Advertiser always tell you the profit not the liability that comes with the profits. A part of story is from https://www.youtube.com/watch?v=cTYtImtffZY. You can also learn about hight risk of law suite for running an E-commerce business: https://youtu.be/_g13W5_1lZY.