What is Drop off in Google Analytics?
"Drop off" reflects the page on which visitor left an identified "Visitors Flow" - the intended flow of your traffic - and went down a path different than the Visitors Flow.
A drop off means that the user left the website after that page. Either that or his cookie got reset, which again is more likely when the user has stopped interacting with your website.
Drop off is also known as a bounce rate of the user from one page to another. For this quick scenario it is also called a bad experience from the website page.
According to Google, Visitors Flow is a graphical representation of the paths visitors took through your site, from the source, through the various pages, and where along their paths they drop off your site. It uses "nodes" which show the metrics used (countries, pages, group of pages etc.) and the paths or "connections" from one node to the next.