You can think of the file revisions as a history of the changes made in a file along the way. From the web app you can view or revert old versions of your files. File revisions are represented by modification time and date and are kept for a different period of time, depending on your pCloud plan:
Free - 15 days
pCloud Premium/Premium Plus/Lifetime - 30 days
Want to extend the period up to which you can use file revisions? Extended File History is available as an add-on to your pCloud account. Extend now!