The label 'Other' is applied by the system to files that don't fit squarely into those types, such as installer packages, cache files, old backups, app extensions, temporary files and the like. Tested on production 1.4GHz quad-core Intel Core i5-based 13-inch MacBook Pro systems with 8GB RAM, 256GB SSD, and prerelease macOS Big Sur. Tested with prerelease Safari 14.0.1 and Chrome v85.0.4183.121. Performance will vary based on usage, system configuration, network connection, and other factors.
When you look at the SSD disk drive via Disk Utility, does it show the partitions or other things in the solid state drive like Recovery? If so, that kind of area should be kept and avoid erasing that area in hopes of using it.
With a relatively small capacity internal storage area, there are several things in there which would be considered essential, so if you try & remove things, be sure they are mostly things you have put there.
You may need to consider an external drive or other device for extended storage; some of them may allow you to access files easily from applications on demand. Other kinds could hold a bootable backup of your system that is not a TimeMachine or Recovery setup. If you do go with additional storage capacity, it could be partitioned for a variety of reasons.
The total allocation of system resources, storage capacity (free space vs used), virtual memory, installed RAM, and what is using it, etc can be checked over in Activity Monitor.
There are limited user upgrades to hardware in a MacBook Pro or Air, a tech could upgrade the SSD to a larger capacity, and if there is a RAM (memory) upgrade available, that could also be done. Like the battery, some of these things aren't something an end user will personally address in a DIY takepart. But some do.
Good luck & happy computing!
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