Where can I get opencart variables for my custom file and how to connect this file with variables to my custom file for

I need help, namely, I need to use the variables that are used in product.tpl in my opinion.tpl created feedback file (this is how I called it) and the question is how to use these variables if I connect with jquery(event click) opinion.php file in the main file, but I can not use variables and how to connect this file with variables to my custom file for further use?

Then you need to understand MVC.

Read this from start to finish then try again:
https://code.tutsplus.com/tutorials/fro ... -cms-21627

If you're still stuck, come back then.