It seems that you want to know more about what is being stored as "Other" in your storage space, and I'm happy to provide some help for this.
Check out what the following article has to say about this:
What is 'Other' and 'Purgeable' in About This Mac? - Apple Support
In OS X El Capitan or earlier, “Other” files are those that your Mac doesn't recognize as belonging to any other category. These include files within disk images or archives, data stored by apps such as Contacts or Calendar, and app plug-ins or extensions. When your Mac is in Safe Mode, all files are categorized as Other
The following article offers some advice for managing your storage space. While most of the information is intended for macOS High Sierra, there is some advice that will work for you as well:
How to free up storage space on your Mac - Apple Support
How to free up storage space manually
Even without using the Optimized Storage features of Sierra or later, you can take other steps to make more storage space available:
- Delete files that you no longer need by moving them to the Trash, then emptying the Trash. The Downloads folder is good place to look for files that you might no longer need.
- Move files to an external drive.
- Compress files.
- Delete unneeded email: In the Mail app, choose Mailbox > Erase Junk Mail. If you no longer need the email in your Trash mailbox, choose Mailbox > Erase Deleted Items.
Thanks for using the Apple Support Communities. Cheers!