The puzzle asks us to look for ...
... countries whose shapes resemble the given geometric shapes as closely as possible in the given continents – it's a "closest-to" puzzle.
Most circular country in Africa: SIERRA LEONE
Squarest country in Africa: EGYPT
Triangular country in Central America: NICARAGUA
Hexagonal country in Europe: FRANCE
(France is sometimes referred to as the Hexagon, so that made me think of the similarity of the shapes. From just looking at a map of Africa, I considered Sierra Leone, Lesotho and Eswatini as circles and the mainland of Equatorial Guinea as a rectangle, but an internet search brought up this article, whose answers neatly fit the number of blanks in the puzzle.)
The overall answer is:
"COUNTRY-GONS", that is country shapes that are nearly regular polygons. You get it if you write the four coutries above in the given pattern and extract the numberes letters:
(S) I E (R) R A L E (O) N E E G (Y) P (T) N I (C) A R A (G) (U) A F R A (N) C E
11 6 2,9 7 5 1 8 3 4,10