On x10hosting, your personal file system starts at /home/igor , where igor is your cPanel username.
Your Document Root, the files that are directly accessible via the web, starts at /home/igor/public_html
A PHP script can access any file on your personal file system.
So, if you want to have files accessible by scripts but not directly via the web, create a directory, /home/igor/includes , and place the files there. When you require them in your PHP script, remember to use the absolute path.
Alternatively, you can put them in a directory, /home/igor/public_html/includes , and then password-protect the directory.