Hello, MichaelJonas.
“Other” storage on Mac is files that don’t easily fall into the clearer category labels like “Audio" or “Photos”. The types of "Other" files would include:
• Cache files like user cache, browser cache, and system cache.
• Documents like PDF, .psd, .doc, etc.
• Disk images and archives like .zip and .dmg.
• macOS system and temporary files.
• App plugins and extensions.
• Everything else that doesn’t fit into the main macOS categories.
• Things that Spotlight doesn’t recognize as belonging to other labeled categories.
You can't manage the contents of this category. The contents are managed by macOS, and the category varies in size depending on the current state of your Mac.
What you can do...
• Make sure you have emptied the trash.
• Empty the trash in the Photos app.
• Delete unused and unneeded installers from your downloads folder and desktop.
• Try reindexing Spotlight. That may help it recategorize the document types.