what is 'process.binding('config').preserveSymlinks' in module.js

There is a piece of codes in module.js in node

const preserveSymlinks = !!process.binding('config').preserveSymlinks;

I can't figure out what preserveSymlinks mean and it uses in the Module._findPath()

here is preserveSymlinks in the Module._findPath()

My question is:

• What does preserveSymlinks mean (in Module._findPath())?
• Why use two exclamation marks?(!! process.binding('config').preserveSymlinks)

Thanks for ur answer!

via TristaLee