https://m.academy/articles/magento-2-request-response-lifecycle/

https://tiagosampaio.com/2023/06/19/front-controller-the-guy-who-handles-the-request-in-magento-2/

Types of Controller Response in Magento 2 

There are five Controller Response Types in Magento

•  Page
• JSON 
• ROW 
• Redirect 
• Forward

(01) Page: This returns HTML loaded from a layout handle.

(02)

Certification journey for Adobe Commerce Developer Professional

Roadmap and complete guide if you want to be a certified developer for Magento 2

Following are website link which helps you to prepare for exam.

https://www.study4exam.com/magento/free-magento-2-certified-associate-developer-questions