In modern pages SharePoint introduced new webparts one of them is Kindle Instant Preview webpart.
This will render the preview of the kindle book.

Step-1: Go to communications site and edit the page.
Step-2: Add kindle instant preview webpart

Step-3: go to kindle webpage and select the book which you want to embed . Here I am navigating to

Here on Page go to right and you can see embed link . Click Embed link and see embed code in popup. Copy that code and paste in the properties of kindle preview webpart.

When you add the embed code you will notice that it will not render the book and will get a warning like below:

This is not a valid Kindle instant preview link. Find your Kindle book, and then click Embed to get a valid link.

To solve this problem we must go to site settings . In that Page select HTML field security link and go to the page where you will see all the domains which are allowed to embed. In that list add and click ok.
Come to the page where you want to add and refresh the page and add the embed code and finally you will able to see the preview of the kindle book.

You can also see many other properties 1)Size of preview 2)Show Buy Button 3) Add associate Id.

I made a video about Kindle instant preview WebPart . Please watch it and subscribe to my YouTube channel.