https://internetcomputer.org/blog/2023/09/13/news-and-updates/update#moc-0100—motoko-stable-regions
What is a “region”?
A Region is a new Motoko abstract data type that uses an API which exposes low-level canister stable memory. Regions are unique since they use distinct portions of stable memory that never interfere with one another. New Regions can be created dynamically, and any old regions that are marked for garbage collection will be removed and reused for new Regions afterwards.
The bit in italics is inaccurate. I’m not sure how that got out but it is a misunderstanding.