Folders in Impactive are an internal organization system within the admin dashboard. They help you keep your actions, contact lists, user lists, tags, and custom fields organized - this is particularly helpful if you are running a lot of program from your Impactive dashboard, and need to be able to find thing more easily.
You can create and manage folders in Data > Folders.
Once a folder is created, you can add the following Impactive components to that folder (use Add to Folder at the right-hand side of the row for a certain action, list, etc.):
Actions
Contact lists
User lists
Tags
Custom Fields
Within any of those component types, you'll be able to filter by folder to locate only the actions, lists, etc. within that folder.
Folders are not the way to determine which actions are published and visible to which users/teams, to share actions with affiliates in coordinated campaigns, etc. They are purely an internal organization tool within your admin dashboard.