https://www.barilliance.com/dynamic-content-examples/....

first result on searching "Dynamic content" in Google

Have you ever seen Contents, pricing, offer valid till date and such stuff
changes everytime when you visit a site? That's what dynamic content is. Even
though there is the term 'Content' in it, it's basically done as Arbab ji shared
a link, 'For Better Conversion'. It has nothing to do with text. Instead its an
HTML code as far as I can recall that's inserted in the Web page code or stuff
like that, duh.

You change the content what an end user sees on the web page based on the user's
behavior on the website.

Let's take an example of hero image.

1. First time user you might tell them about what do you solve.

2. Second time user you might show them your latest ebook waiting for the user
to download.

3. Third visit, you can aks them about the ebook they downloaded last time.

This is only one simple plain usecase. It can scale up with multiple trigger
points.

Basically, different users see different contents on the web page based on their
behavioural patterns the website analytics captured.

A better term you can Google to research more is personalization.