Is there a relation between SharePoint framework and PNP and CSOM ?
Can I use SPF X with SharePoint on prem ?
I need to start learning Sharepoint framework and need to know how to start
The SharePoint Framework (SPFx) is a page and part model that enables client-side development for building SharePoint experiences. It facilitates easy integration with the SharePoint data, and provides support for open source tooling development.
To start learning SPFx check Welcome to the SharePoint Framework Developer Preview!
PNP stand for Developer Patterns and Practices that is initiative provides samples and documentation to help you to implement typical customizations for Office 365 or for SharePoint (Online and on-premises) based on your functional requirements.
PNP can be run also on ShareePoint On-Prem but you'll need to make some changes to the solution that you want to run. for more details check How do I run the Office 365 Developer Patterns and Practices against SharePoint 2013 On Premises
To start learning PNP check Office 365 development and SharePoint patterns and practices solution guidance
CSOM stand for he client-side object model (CSOM) that provides client-side applications with access to a subset of the SharePoint Foundation server object model, including core objects such as site collections, sites, lists, and list items.
The CSOM actually consists of three distinct APIs—the
To start learning CSOM check Using the Client Object Model
SharePoint Framework (SPFx) is something completely new and it doesn't have direct relations to pnp and CSOM (besides some guys from PnP team involved into SPFx program too). SPFx is a new page and web part model, allowing you to create rich UI experiences with modern technologies.
For now it's not available for on prem, but there are plans to add it. Per this comment by Bill Baer here - The SharePoint Framework—an open and connected platform - We have plans to bring the SharePoint Framework to SharePoint Server 2016 through our Feature Pack model as announced on May 4th. Timing and availability are TBD; however, we will make available our 1st Feature Pack in CY 2017. Current version (Novermber 2016) is not final, available only to First Release tenants and only Drop 5 was released recently by the SPFx team.
To start learning just open github sp-dev-docs, scroll a bit to "Get Started" section, click on a few links and your journey has begun! :)