I assume that you are asking here about the market orientation for making a business profitable. This is an orientation in which the firm is trying to become profitable by making sure that it has the right product. It tries to determine what customers want and then to tailor its products to them. This is in contrast, for example, to firms that have a product orientation. That is a strategy in which the firm tries to perfect its product and to gain customers by having a great product.
The question, then, is how the firms determine what the customers want. The main way to do this is by carrying out market research that will determine what customers want. Market research can be done in a number of ways. One way is to study what customers actually buy. This method can help a firm to determine what products or services are in greatest demand. A second, and more effective, way to do this is to ask customers about what they want. This is often done through focus groups. Firms will hire other firms that specialize in conducting focus groups. These groups talk to groups of customers and get them to discuss what sorts of things they like and do not like with regard to certain kinds of products. These focus groups help to allow firms to understand how they should change their products.
Thus, the main way for firms to determine what customers want is through market research.