Framework
A framework is a ready-made base for building sites or apps, with the common parts already done.
In a simple example
Instead of writing page routing and layout from nothing, you start from a framework that already has them.
Why it matters to you
AI coding tools usually pick one for you, so you will see its name in your project.
Do not confuse with
A framework is bigger than a single piece of code. It sets how the whole project is arranged.