Note: You can gain a better understanding of Blocks & Sections by inspecting this image here.
It is essential to add a Section::(Block Wrapper) before starting and breaking other blocks to ensure proper arrangement and functionality.
A shortcode is a small piece of code enclosed in square brackets, like [shortcode], that performs a specific function or displays content on a website. Shortcodes are commonly used in WordPress and other content management systems to add dynamic elements, such as forms, galleries, videos, or custom functionality, to a webpage without writing complex code.
The Blocks supports shortcode as well, you can add blocks by adding you custom shorcode from anywhere to given shoortcode field.