Mac storage basics · Library folders explained
What is the Shared folder in Users, and can I clean it out?
Short answer: It's a folder all accounts on the Mac share, and some installers store big content there. Check it via Go → Go to Folder, and remove only items you recognise as no longer needed.
Users → Shared is a folder every account on the Mac can read and write, used to pass files between users. Some apps and installers also park content there — for example large sample libraries or downloaded installers.
It's worth a look when space is tight: open it from Finder with Go → Go to Folder… and type Macintosh HD › Users › Shared. Delete what you recognise as no longer needed, but leave folders that belong to apps you still use, since their content may live only there.