its machine code, like any other dll. So its not entirely human readable, its not entirely computer readable either however it is possible to read nonetheless as a symbiosis of theese two. All you need is the libraries and good debugger. its not necessarily fun but you can do it, in exact same way as you can read eny exe file also.
However also often highly illegal.
Anyway you should ask this on a programming forum. but it requires you to understand programming quite deeply.