I need to use the RFID-RC522 module in my Johnny Five project (it is an NFC reader).
There is an arduino Library that makes it easy to interface with that: https://github.com/miguelbalboa/rfid
Can i use this library through Johnny-Five? If yes, how?
Short answer: Yes.
Long answer: You'll need some work.
JohnnyFive uses Firmata to interact with Arduino. Firmata is a program you upload on the Arduino that will allow you to interface it easily with your computer using different languages such as Python, JS, C/C++ and so on.
Your problem is that you cannot have Firmata and a custom program using the RFID library on your Arduino at the same time.
So you have to choices:
The second solution will be easier and simpler if you don't need Johnny five.
As you said you are new to Arduino Programming, I would advise you to start small with just Arduino code before moving to Arduino+JS.
Hope this helps :)