Page Builder is a new feature added to Magento starting with Magento version 2.4.3. Page Builder is for creating content by dragging-and-dropping pre-built controls.
Here in this blog, we will see what is Page Builder.
And how we can use it to create content in our Magento instance.
Page Builder controls are also called content types there are four content types available shown below.

You can use all of the contents shown above by dragging and dropping them. And you can also change settings for individual contents like margin, height, width, padding, etc. You can check the video to see how you can add content to a page.
You can enable/disable the Page Builder from the admin configuration as shown in the below image.




If you enabled the Page Builder then you can see the “Edit with Page Builder” option on the content page creation, block creation, and product content description section.




You can also check the content created in different viewports to ensure the responsive behavior of you content as shown in the below image.




You can check the Magento blog for Page Builder
https://developer.adobe.com/commerce/frontend-core/page-builder/
You can also check out other blogs
https://webkul.com/blog/magento-2-how-to-configure-and-customize-system-xml/