1973 Dodge Dart Swinger Front bumper filler
This screw location is the mounting point for the entire lower left corner of the grill, including that strip that is missing.
Betcha if you look up under the grill you will see where it either broke or was cut off for some reason.
Look at the blown up pic of that same area and you can see the same vertical ribs that are part of the rest of the grill.