Dwell Time is the amount of time passed in between when a user clicks on a search result (website) and then returns back to the search engine result pages (SERP).
A less than 5 second can be said to be a Short Dwell Time and can be an indicator of low-quality content on the search engine result pages.
A good Dwell Time can be said to be 1–2 minutes. A good Dwell Time is a boost for the website owner as it is an indicator of visitors reading their content.