In Legends of Runeterra, there are six regions: Demacia, Freljord, Ionia, Noxus, Piltover & Zaun, and Shadow Isles. Regions act as card factions from which you can build decks from. In the constructed format, you can have a max of two regions in your deck. The draft format currently does not have a limit.
Bilgewater- Bilgewater has an explosive playstyle with mechanics that can be risky but really reward you for being able to think ahead.
Demacia- Demacia’s playstyle centers around building armies of resilient units that can buff each other and maintain a persistent board presence. The region allows you to influence the flow of battle by forcing combat.
Freljord- Freljord uses crowd control effects and mana ramp mechanics to finish the match off with powerful late game threats. It has the biggest units in the game.