If I paste a string from some web page into an Emacs buffer sometimes it will show the Unicode representation of some characters with a backslash and some octal code. How can I convert this to the character representation?
Specify whether you are using Emacs in a terminal or GUI Emacs.
Use a font in Emacs that can display that Unicode character.
If your buffer is Unibyte (single-byte), then consider using multibyte instead. In any case, see the Emacs manual, node Unibyte Mode and the Elisp manual, node Text Representations. Consider using function
set-buffer-multibyte to convert the buffer to multibyte. See also (elisp) Disabling Multibyte (not to disable it, but for more info about it).