What does it mean (Search Result Page in AMP)?

It is an option that lets you decide if you want your search pages/posts to load as the AMP version. If disabled it will fire the non-AMP pages, and otherwise if enabled.

The “search” implies; the search you make for pages on your website, and not Google search.
Screengrab for reference: https://prnt.sc/10io4y7
I hope I was able to answer your question.
Feel free to write back if you have any more. ??

When I click on search results that have the amp in last in desktop it opened in amp…I don’t want that…Whenever I opened posts from search results on the desktop they are opening in amp and not in desktop theme. How to correct this?

Here is the image for better understanding:- https://prnt.sc/10iod0o

• This reply was modified 3 years, 8 months ago by userpankaj.

Could you please send us the exported file of AMP Settings so that we can have a look at your set-up?

Here is the tutorial link regarding how to export amp settings:
https://ampforwp.com/tutorials/article/how-to-import-and-export-the-amp-option-panel-settings/#export-options