This doesn't contain any spoilers, so you can read it for a deeper understanding of the subject or skip it and gradually learn about it while reading the novel. Reading this, though, may give you a better foundation.
Summary: There are five major nations that are in this series that are on the planet of Terrathis, which are: The Tarondar Kingdom, The Veltharian Republic, The Seylora Theocracy, The Orvienth Empire, and the Ryndoria Kingdom in no particular order. The Tarondar Kingdom though is the main nation the series takes place in. These nations are all on the continent of Glozaria. (There are other continents but you won't need to know about them until Volume 2.) Tarondar being right in the center of the continent.
The nations that have the word "Kingdom" run on something very similar to the Feudalism. Presidents lead republics, which are democracies, and emperor's rule empires.
[Tarondar and Ryndoria Kingdom Titles + Info]
(Keeper) King - Refers to the King of Tarondar, who leads the Keepers and everyone in Tarondar. (See Magic System document for more information). I will include some numbers down below each title, just for reference in different sizes for the population.)
Grand Duke = Controls several cities (60k+ people)
Duke = Controls a city (30k+ people)
Marquess = Controls a small city (15k+ people)
Earl = Controls a town (10k+ people)
Viscount = Controls a large village (5k+ people)
Baron = Controls a village (1-3k+ people)
- Note: The Oriventh Empire structure is very similar to the Kingdom's structure, except they have multiple Kings that server under the Oriventh Emperor.
[Veltharian Republic Titles + Info]
President = Leads the entire nation
Vice-President = Assists the President and helps lead when needed.
Assembly Member = Elected citizens from each Veltharian city to vote on policies from popular vote.
[Seylora Theocracy Titles + Info]
The Divine One = Leader of Theocracy
Seylora Cardinals = Cabinet of The Chosen Priest
Archbishops Council = Also known as Holy Council members. They help lead the country alongside The Divine One's chosen orders.