what is JRF and why we need it

what is JRF and why we need it

I've never heard of any JRF. Post a link to the reference for that term.

There is a JRE that is the Java Runtime Environment - perhaps that is what you are referring to.

If so you need it to run Java. Just search the web for JRE and you will find PLENTY of links about the JRE. Here is one to get you started.

Ensuring the Presence of the JRE Software (The Java™ Tutorials > Deployment > Deployment In-Depth)