It allows you to add multiple system users at once. This saves you from having to add users one by one. In addition to basic customer data (phone, email), you can also import more detailed data that is available to you. You can do this by an import CSV files operation,  uploading Xml files, importing from a database, or using other input files. Be careful to adhere to the required file size or any other restrictions the system you're working with might have.