There's a method to have a text file on my small server, but that only my php and python scripts would have the ability to see clearly, and when the consumer just type the link to the file will get yourself a forbitten condition?

I'll prefer to ensure that it stays within the website directory, httpdocs (or httpsdocs, maybe).

Tha file will contain my database user and passord, and other stuff like it: must be in text-format becose i need to have just 1 file but i'll need to read it by many languages (php and python for example) in an easy way (probably in json structure)

So does not matter when the file extension could be .txt, could be anything you like more, however i only need when the customers cant visit http://www.example.com/myfile.txt or download it by ftp.

Is possible, with a few apache configurations (chmod? not..) or otherwise?

put b .htaccess file inside your directory and deny use of your file such as this:

<Files file.txt>
Order allow,deny
Deny from all
</Files>

You could attempt encoding you text file in Base 64 (or something like that similar) that's simple to implement/has implementations in a variety of languages.

Begin to see the Wiki article on Base 64 encoding

Put the file outer the document directory (e.g rather than /var/www/public to /var/www/private) and provide rw permissions towards the apach for this dir, but don't enable it in apache.conf