Adding folders is a key feature of Document Libraries in Sharepoint Online. It allows users to better organize files and keep things up to date. One of the main advantages to Folders in Sharepoint is that you can share a direct link to that folder with other Sharepoint users. Keep in mind, though: user permissions are inherited from the document Library- which means the users you are sharing with will need access to that library first, or you will need to grant them access specifically to that folder.
To add folders to your Sharepoint Document Libraries:
To share this folder, or add it to a Quick Links webpart:
To change the properties of the link: