It means that there is something wrong with the edit that you have made to line 56 of your includes/languages/english/index.php file.

Difficult to say what that error might be without seeing what you have done to that line. One possibility though might be that you have included apostrophes in your text without "escaping" them, i.e. preceding them with a backslash, "\", so that PHP knows that they are part of your text and not part of its syntax.