What are Model Driven Apps and how to create those?

In PowerApps, you can create two types of apps. First: Canvas App - connected to almost 200+ different data sources, Second: Model driven apps - connected to CDS (Common Data Service). Refer this article to understand what is CDS?

What is Model Driven App?

As name suggest – its app driven by data models.
Its an GUI to manage data in Common Data Service (CDS) databases
Need PowerApps per user or per app licenses or Dynamics 365 subscription
These are component focused no-code design apps
One model driven app can be connected to multiple entities (tables in CDS)
You should prepare your data model before your create a model driven app
You need to create business process FLOWs to control how data is managed
You can add components like entities, dashboard, business process flows, Forms, views, Charts to model driven app
For an entity you might have created multiple views, charts, flows – in your model driven app you can choose as per need.