PubNub's Files feature enables users to upload and share files such as videos, images, or documents up to 5 MB, managed by the Message Persistence storage service, allowing operations via the History API when Message Persistence is active. When a file is uploaded to a channel, it is stored with a storage service and linked to the user's key, and subscribers to that channel receive an event containing file details. Users can learn how to enable Files in their PubNub keyset through a video or step-by-step guide, and further information is available in PubNub's official documentation. The setup process involves logging into the Admin Portal, accessing the keysets page, enabling Message Persistence, and selecting a storage region and retention period before saving changes.