Re: what is a fork?

A fork is when you take the source code of a project and then create a new one from it independently. To make it short, It's when you clone a project to make another one with some changes.

The term applies to cryptocurrency but it can be about a browser, an operating system etc.
For example, Qupzilla is a fork of Mozilla, Mozilla is a fork of Seamonkey. Kubuntu is a fork of Ubuntu, and so on. It's just a term in software engineering

As related to Bitcoin you can read this to understand better what it's about: https://blog.coinbase.com/what-is-a-bitcoin-fork-cba07fe73ef1

Would there be any copy right issues?
I don't even think that those laws are applicable here,but still I'm curious

Laws, really? There isn't any regulatщкы on cryptocurrencies market. The same situation is true for blockchain software...

There won't be any copy right issues.
When codes are uploaded to GitHub and set to public, you grant other GitHub users the right to fork your repository(aka clone your code).