Bounce rate refers to a number, usually shown as a percentage, of users of a website or web application who exit after viewing the very first page of a site
after clicking on its search result.
Bounce rates may be a neutral or bad indication of your website traffic, it depends on what kind of website you are running.
If you are running a blog, where people would usually land on the page they wish to see, a high bounce rate is perfectly normal. If your website has many pages or possibilities of interaction, you might have to look into improving the SEO (Search Engine Optimisation) of your website of web application or you may have to look into improving your product or service if that is the purpose of your site.