I don't understand this part

> To protect against this, you need to use this PHP function:
> mysql_real_escape_string()
> This function escapes (makes safe) any special characters in a string (programmers call text a 'string') for MySQL.
> Example:
> $name = $_REQUEST['name'];
> $safe_name = mysql_real_escape_string($name);
> Now you know the variable $safe_name, is safe to use with your SQL code.