when you land a page and if you exit from that particular page, that is called as bounce rate, based on this Google may give bounce rate to check your website quality with visually.
When a visitor is landing on your home page or any particular page and after spending some time if that visitor left your website from that page then that visitor is consider into bounce rate. i.e if a visitor bounce back form same page then and then only it is consider.
Bounce rate is the number of visitors that source a website through a search engine but leave without navigating to any other webpage and “bounce” back to the search engine to find another resource. A high bounce rate will affect search engine position because it implies to the search engines that the website is not relevant to the searched terms that people are locating the website through and will consequently penalize the website which will ultimately be reflected in its search engine position.
Bounce rate is an Internet marketing term used in web traffic analysis. It represents the percentage of visitors who enter the site and then leave rather than continuing to view other pages within the same site. Bounce rate is basically calculated on how much time a person spends on your site.