Please explain this graph and the paragraph underneath, step by step, thanks

Individual Firm FIGURE 12.12 A Price Level that Generates Economic Prot At the price level P = 10/unit, the rm has adjusted its plant size so that SMC] = LMC = 10. At the prot-maximizing level of output, Q = 200, the fnm earns an economic prot equal to 600 each time period, indicated by the area of the shaded rectangle. The situation depicted in W is inherently unstable. The reason is that positive economic prot creates an incentive for outsiders to enter the industry. Recall that the average total cost curves already include the opportunity cost of the capital that a rm requires to do business. This means that an outsider can buy everything needed to duplicate the operations of one of the existing rms in the industry, and in the process earn an economic profit of 600 each time period