How to get information from a database with a given structure?

Question

PostgreSQL

Hello!
There is a premonition that the question is stupid, but my knowledge of the database is clearly not enough.
Task:
Framework - Yii2, IDE - PhpStorm. The dict
section of the database contains tables. Get a list of all countries from there, etc. Problem: Never encountered a similar situation. I have always dealt with tables that are in public->tables . And migrations there have always been added by default. Question: What is going on here? How to set up a connection to a dict and generate a model based on it?