Shiny Tutorial Lesson 5: How to add counties name on the map

I think both of these questions are more about the maps package than R.

map From maps v3.3.0
Draw Geographical Maps
Draw lines and polygons as specified by a map database.

Country labels, I think you use map.text

A good way to get help would be to create a REPRoducible EXample (reprex)? A minimal reprex makes it much easier for others to understand your issue and figure out how to help.