What do icons mean on top right of a directory in Nautilus?

Question

In Nautilus there is a directory that has an 'emblem' on its top right corner:

What is this icon? What does it mean? And more importantly: How to make it go away?

• Renaming the file removes the icon, but renaming it back also brings the icon back
• On Nautilus Properties there is no icon selected, and it doesn't display it

Favouriting the file produces a similar effect:

The directory is called "Documentos" (Portuguese for "Documents"), but no other file produces the same effect.

Answer 1

It doesn't mean anything, it literally is a custom emblem set on the directory through its metadata. Older Nautilus versions used to let you do that (through the file's "Properties" window):

The 'Emblems' tab was removed somewhere around GNOME 45, but the functionality remains. You can install Thunar to manage them as it uses the same GIO/GVFS framework (and still has the 'Properties > Emblems' tab unlike Nautilus/Nemo), or you can manage the metadata::emblems attribute through GIO tools directly:

$ find /usr/share/icons/ -name 'emblem-*' -printf '%f\n' | sort -u
emblem-documents.png
emblem-important.png
emblem-mail.png
$ gio set -t stringv ~/Example/ metadata::emblems documents important mail urgent
$ gio info -a metadata::emblems ~/Example/
attributes:
  metadata::emblems: [documents, important, mail, urgent]
$ gio set --delete ~/Example/ metadata::emblems