Your work and data are valuable. The HFS backup service exists to provide a campus-wide backup of data on desktop machines, laptops and servers to an off-site location.
Oxford University staff, senior members and postgraduates can use the service, but not undergraduates.
The service only keeps two versions of any file you backup, the most recent and the version immediately preceding that. In this way the service differs from other consumer products like Dropbox or Time Machine, which keep multiple backup versions of files. The practical consequence of this is that the HFS backup service is a 'disaster recovery' service that allows you to recover files from your system which have been erroneously deleted or overwritten, or from a machine that has been lost, stolen or damaged in some way.
It does not offer a 'point-in-time' recovery of your data like services such as Time Machine on a Mac, but it has the advantage of creating an offsite backup which safeguards against fire and theft.