What Is PowerApps

PowerApps is the collections of apps, services, connectors and different data platform which provides rapid application development environment to build a custom apps.

Using this PowerApps we can build custom business apps as per our business requirements.
These PowerApps custom application support the different online and on-premise data sources like (Excel, Office 365Share Point, dynamics 365, SQL Server etc).
Using this PowerApps application we can transform our manual business processes to digital , automated processes.

These PowerApps can run easily on browser and mobile devices.
It’s a new feature to build a business apps without coding.
It’s also provides a platform to developers to interact with data and metadata.

using PowerApps we can create three types of apps:
1. canvas :  Start with blank apps.
2. model-driven : Start with data model first.
3. portal : Used to create external website.

Common Data Service : is the data platform that comes with PowerApps and allows you to store and model business data.
It’s the platform on which Dynamics 365 applications are built;
if you’re a Dynamics customer, your data is already in the Common Data Service.

For more information visit Microsoft site.
https://docs.microsoft.com/en-us/powerapps/maker/index