Local level: your computer
It is wise to create a new folder on your computer and copy all your important data that is spread across dozens of folders into it.
For example, consider the folders for your downloads, documents, photos, and your cloud storage folder. Name this shared folder the "backup folder" for example.
Make sure that this folder is placed on another hard drive or SSD of your computer. This will prevent all your data from disappearing in the worst case if one of your drives fails.
Offline level: external hard drive
To prevent a single point of failure, copy the hospital email lists backup folder to an external hard drive. For 60 euros you can now buy an external drive with 1000 GB of storage space. More than enough for most people. For example, if your laptop is stolen, your data is safe at home on this drive.
The problem of a single point of failure still exists in the form of your home. If there is a break-in or a fire, having your data on two separate devices is of no use. In the worst case, you lose both (assuming you keep an external hard drive at home).
Image of STACK cloud storage
Online level: cloud storage
That's why you need a backup outside your home. A practical and free solution for this purpose are cloud storage services such as Dropbox, Google Drive or Microsoft OneDrive. You probably already use these to sync frequently used documents between your phone and computer.
These services (in the free version) offer a few GBs of free storage, which may not be enough for a full backup of all your files. There are also storage services that offer more (1000 GB) space.
Automate backups
The above backup structure is safe, but also requires the necessary maintenance. You don't want to search for new and modified files every now and then and copy them manually to all three backup levels. Good automation takes this work off your hands.