On the map the circles triangles and squares are all of examples of

Symbols

Explanation:

In map creation, the use of symbols refers to the use of shapes in order to represent an actual physical feature of a region.

Here are how those symbols usually used in the map:

Circles generally used to represent the existence of a city on top of the map.

Triangles generally used to represent the existence of mountains on the region.

Squares generally used to represent the existence of important buildings within the region.