Image next to the system language ... seems to be a blocked video
When I click on it it does not display anything, but it actually popped up after I installed Dropbpox ...
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Sign up to join this communityYou can install the icon for Dropbox manually. Check here
Make sure you have git installed via
sudo apt install git
then execute
git clone https://github.com/zant95/elementary-dropbox /tmp/elementary-dropbox
bash /tmp/elementary-dropbox/install.sh
The icon itself means that there's a program running and the icon specified in its .desktop file cant be found in any of the icon locations.
Its a common thing with Dropbox for example (if its indeed dropbox let me know if you need a fix) Other programs might have this behavior as well.
try clicking it and see which program's menu opens