https://www.joelonsoftware.com/2003/10/08/the-absolute-minim...
Basically, ascii is encoded as integers. '32' represents a space. However, ascii is quite limited and if you want non-US-centric characters, you need to use other character sets. For a myriad of reasons, once you go into unicode (the Universal Character Set) there are lots more options for characters. For example, there are multiple whitespace characters.
http://jkorpela.fi/chars/spaces.html
These exist to give different widths or other adjustments to text that is non-ascii. What likely happened in the post (and what did happen to me) is copy-pasting from some document that changed a normal ascii space (that Ruby would expect and know how to deal with) into a unicode character that Ruby interprets as any other character. It would be like having a stray 'g' in the line, but you, as a developer, don't see it. Fun :)