corner flag
US /ˈkɔːr.nər ˌflæɡ/
UK /ˈkɔːr.nər ˌflæɡ/

1.
a flag on a pole at each of the four corners of a soccer field, used to mark the playing area
:
•
The ball went out for a corner kick near the corner flag.
•
The referee pointed to the corner flag, indicating a corner kick.