Undersatnding why the Unicode error occurs

I need help understanding why the Unicode error occurs anytime I attempt opening my dataset and converting it into a list of list.

This issue occurred in both my 1st and 2nd guided project. Above is a screenshot of when it occurred whiles working on my 2nd guided project.

I solved it using encoding=‘utf8’ provided in the first guided project. However I would like to understand why it keeps popping up and the meaning of the solution provided by dataquest.

I hope this answer on Stack Overflow will help you understand it better.