成本, 利潤, 本金是什麼意思??

Cost. The cost of the product sold or services rendered.
Profit. Gross profit means the profit made on trading of products while net profit on the whole operation after the deduction of operating costs.
Capital. The money you put in your business. The more money you put in, the more profit you are expceting to make. Also a higher return from each amount of capital you put has to be maximised.
The good scenario is lower cost, higher profit and bigger return on capital.