Bounce rate has nothing to do with springs or sponge balls but is instead is a measure which indicates how people engage with a website. For SEO purposes it specifically tells you how many visitors effectively take one look at your site and then leave, versus how many visitors click through to other pages and take other actions on the website.
Unfortunately, Google, as they do with many ranking factors, keep their cards close to their chest. Despite some statements from their representatives claiming bounce rate doesn’t influence their ranking scores, all test evidence and case studies indicate clearly that it does in some way.
For example, analysis from Wordstream showed that for one particular niche keyword search, websites that had a bounce rate of less than 76%, were more likely to find themselves in positions 1 to 4 if all other factors were equal. However, once that bounce rate got higher than 78%, website rankings were more likely to found at the lower half of the results.