There are many ways to understand or to learn bitcoin, there are already many books about it, there is also much news you can read online, an article and forums like this. Among those ways to learn crypto, you may recommend him to join this forum so it would help them to understand more about cryptocurrency. There is much useful information here that talks about cryptocurrency. You may also use google for the things you want to learn about cryptocurrency. Learning about it is not an easy thing because it is really broad, just expect that it would take so much time.