“VLC” is damaged and can’t be opened. You should eject the disk image.

Hi and welcome to the Apple (user-to-user) Community!

It seems you downloaded the VLC media player app, but an error occurred, or it may not be the right one for your iMac.

To locate that downloaded disc image check your "Downloads" folder or maybe check on the desktop ?

(If needed: you could open a Finder window and search for VLC. or for .dmg (disk image)

A right click on the file should reveal a menu which will allow you to choose "eject".

You may or may not want to try to download VLC again:

Seems the Official site for VLC media player has a Mac version available for download.

https://www.videolan.org/vlc/

All the best :-)

Thank you so much for letting us know we helped! Cheers :-)