On the Activity tab and the Backup tab, you can view additional information on a backup, such as backup history and file types the backup contains. The Activity tab contains a list of operations performed on the selected backup starting from its creation, the operation statuses, and statistics. This comes in handy when you need to find out what was happening to the backup in background mode, for example the number and statuses of scheduled backup operations, size of backed-up data, etc.
When you create the first version of a backup, the Backup tab displays a graphical representation of the backup content by file types.
The Activity tab
Nonstop backup and mobile backups do not have an activity feed.
To view a backup activity:

What you can view and analyze:
For more information, refer to the Knowledge Base article: https://kb.acronis.com/content/60104.
The Backup tab
When a backup is created, you can view statistics on types of the backed-up files:

Point to a color segment to see the number of files and the total size for each data category:
Information on the data size: