The structure of folders in a role is standard and you cannot change it much.
The most important folder within the role is the tasks folder, because this is the only mandatory folder in it. It has to contain a main.yaml file that will be the list of tasks to be executed. Other folders that are often present in the roles are templates and files. The first one will be used to store templates used by the template task, while the second will be used to store files that are used by the copy task.