Bounce rate is (an SEO term) the percentage of website visitors who leave (bounce) without visiting another page on that website.
The range widely depending on industry and niche. According to Google, although this rate can indicate potential content or website issues, it is not a direct ranking factor.
Is a high bounce rate a bad thing?
If the success of your site depends on users viewing more than one page, then, yes, a high bounce rate is bad. For example, if your home page is the gateway to the rest of your site (e.g., news articles, product pages, your checkout process) and a high percentage of users view only your home page, you don’t want a high rate.
On the other hand, if you have a single-page site like a blog, or offer other types of content for which single-page sessions are expected, then a high rate is perfectly normal.
You can track this rate by connecting your website to Google analytics so it can track everything that is happening on your website.