Auto Refresh in Kibana

Can someone explain something about Auto refresh in Kibana? What does that feature actually refreshes and how is it useful?

It re-executes all queries to elasticsearch. Many people have dashbaord with a relative time filter, say last 15 minutes, and by turning on auto-refresh they can put the dashboard up on the way and it will always show the most recent information (rather than only information from when the page was originally loaded).