Read more here: https://beautifulweb.pl/prestashop-module-development-where-to-start-2/
PrestaShop documentation provide a basic guild-line on how to create own plugin i PrestaShop.
https://devdocs.prestashop.com/1.7/modules/creation/
How to use importer components
https://devdocs.prestashop.com/1.7/development/components/import/
Fundamentals:
https://devdocs.prestashop.com/1.7/basics/introduction/
Information about new architecture CQRS in PrestaShop 1.7+:
Older but also useful relevant
Udemy:
https://www.udemy.com/course/create-module-prestashop-1-7/
Inne przydatne źródła informacji:
https://allegro.pl/pomoc/dla-sprzedajacych/wystawianie-i-edycja-oferty/masowe-wystawianie-ofert-z-pliku-csv-a1zLdKKkzub
https://www.joeldare.com/wiki/php:converting_xml_to_csv_with_php