What is backend?
The backend is the part of an app users don't see — the database, authentication, business logic and APIs that store data and enforce rules.
A convincing prototype still needs a backend to be a real product: somewhere to store data, a way to sign users in, and logic that runs securely on a server.
BerryBell generates the backend for you — database and API, plus auth on paid plans — so a build is a working app, not just a UI.