This statement is true. The main function of Management Information Systems (MIS) is to provide the management in a firm with a wealth of data. This data can be used to help the management know how best to manage their firm.
An MIS is a system that is set up to gather data that is of use to the firm. A retail firm might collect data about such things as what products are bought most at what time of day. It might collect data about which areas of the store are most often visited. It might collect data about where customers most commonly need help from staff. All of these kinds of information can help management manage. These kinds of information can help management do things such as deciding where to deploy staff members at certain times of day.
Management typically needs a lot of information in order to understand the way that the firm is running. MIS can collect this information and feed it to management so as to allow management to understand the firm and manage it more effectively.