Redux is a framework that controls states in a JavaScript app. According to the official site:

Redux is a predictable state container for JavaScript apps.

There are many states in an app that will change depending on time, user behavior, or a plethora of different reasons. Thus, if we consider an app as the process to change its own state, the view a user sees is how the states are presented.

Related Articles:

https://www.codementor.io/reactjs/tutorial/intro-to-react-redux-pros