Both the program and the database run in the "cloud" (the user can use it with a browser), no own resources are required either at the device or operational level.
The advantage is that you don't have to take care of data backup, virus protection and updates, you don't have to buy a server, your costs will be more predictable and the version tracking fee is included. In addition, the expenses and tasks associated with installation and updates will not be burdened by you, while the security of operation will be higher in most cases - contrary to beliefs.