Mac "Other" storage holds files (documents, photos, apps, movies, audio, etc.) that macOS is unable to classify into any known format. Cache, temporary, and other file kinds can quickly fill up the Other folder on Mac.
If you find the Other category occupies a lot of disk space, you can read this post What is 'Other' on Mac Storage and How to Delete it to delete unwanted files in it.
Besides, the Documents category Mac storage isn't equal to the Documents folder in Finder, it holds files in your home folder that aren't grouped in other categories, such as Pages documents and PDFs. On macOS Ventura and later, after you check the storage from System Settings > General and choose Storage, you can click the info button beside the Documents to view the item within it.
If you need to free up disk space on Macintosh HD, you can easily make it with a third-party Mac cleaner such as iBoysoft DiskGeeker, the features it provides like Clean Junk and Space Analyze can help you easily unwanted files on Mac.