This is most likely due to the character set or encoding setting in the spreadsheet application you're using.
You'd want to set the character set to Unicode (UTF-8). LibreOffice and Google Sheets already have these set by default and they'll be able to display the special characters properly instead of showing weird symbols with accent marks.
Excel for Mac unfortunately doesn't support UTF-8.
For Excel on Windows, you can try the following:
Free alternatives to Excel that support UTF-8 encoding: