The quotes in your string are extended characters.
You could fix this problem pretty quickly by simply replacing them with standard "
quote characters rather than the curly quotes “ ”
you've got now.
However, in the long term, you probably need to be able to handle extended characters, as it includes all kinds of things you're likely to need in your text, not just curly quote marks.
To fix this problem properly, you need to ensure that your system uses UTF-8 encoding at all levels. This includes within the database, your PHP code files, and the data that is sent to the browser.
I suggest reading up further on this here: UTF-8 all the way through