What do you call this type of plug?
This seems to be a fork terminal for a grounding lead. One's supposed to mount that to a grounding post, as illustrated on this wikipedia page.
Do not forget to slide back the protective plastic cover, so the metal connection makes contact with the metal exposed by the grounding post. The screw of the grounding post goes between the two metal prongs.
Installing the grounding connection is generally recommended. Do consult the manual.
Alternatively, if the cord is removable from the monitor or its power supply, and you have grounded (3-hole) sockets available instead of the grounding posts, you can likely use the usual 3-wire grounded power cables in this cable's place.