Get Correct Storage Information
Do not use the information from the Storage section of the About This Mac dialog. Ignore the Storage information as it is typically wrong. To find out the correct information for any disk: Select a Desktop disk icon. Press Command-I to open the Get Info window and look at the topmost panel displayed. You will find the disk information displayed for Capacity, Available, and Used. If you have more than one disk/partition then repeat for each one on your Desktop.
The categories found in the Storage section of About This Mac is simply an arbitrary way of displaying files on your drive. There are no such categories actually on the drive.
"Other" contains any of the following types of files. They cannot necessarily be deleted wholesale. Furthermore, “Other” is not an actual, physical file. Rather it’s an arbitrary category to which the files are assigned.
- System temporary files
- macOS system folders
- Archives and disk images (.zip, .iso, etc.)
- Personal user data
- Files from the user’s library (Application Support, iCloud files, screensavers, etc.)
- Cache files
- Fonts, plugins, extensions
- Hidden files
- Other files that are not recognized by a Spotlight search
See What is 'Other' and 'Purgeable' in About This Mac?