ipairs is the list. pairs is the map.

Goal

Print list cities, then map units.

for i, city in ipairs({"Nairobi", "Mombasa", "Kisumu"}) do
  print(i, city)
end

local units = { Nairobi = 12, Kisumu = 5 }
for city, n in pairs(units) do
  print(city, n)
end

local cities = {"Nakuru", "Eldoret"}
for i, city in ipairs(cities) do
  print(i, city)
end

print(#{"Nairobi", "Mombasa"})