Rss stands for realy simple syndication.With the help of rss it is possible to distribute up to date web content from one website to thousands of other websites.Rss files can be automaticaly updated.With the help of rss feed users can check their website faster using rss aggregator.
I have limited experience with RSS feeds. I tried adding it to one of my sites several months ago to try to build more traffic and saw no change at all. Social media has pretty much killed the use of newsreaders, so unless your feed happens to appear on a site somewhere you're not going to get any visibility to speak of. I wouldn't disable news feeds on an existing site, but I wouldn't go to any special effort to add it anywhere.
I think RSS feeds are still important because, if you are a website owner it helps you promote and share your content, and if you are a reader it provides you the content. It's still helps you getting traffic, because people loves various RSS readers such as Feedly where they find and read the content they love.
Yes, still in presentmarketing world, rss feeds are still proves out to be the most important factor for search engine rankings and in SEO. So, it is best ot use that technique to increase your website's search engine rankings.
Now days RSS feed is pretty old idea for getting traffic. This because popular search engine doesn't give so much importance to RSS feed. RSS feed generally update automatically (if not created manually), so it's good way to reach your blog readers.