how my website can be benifited with rss feed what is this

I am not quite sure what you mean. But I supose your website could benefit from rss feeds because you will receive up-to-date content on your site from major news site like the bbc and digg. That is how you can benefit...

I hope that was what you were looking for.

you could also serve RSS to your users.. but serving RSS to humans is only really of benefit if your site publishes important information frequently, and if people are sufficiently interested in that information.

you can use RSS sort of like textual radio: if my desktop RSS aggregator is listening to one of your webserver's RSS feeds, it will make a "ding" noise when it notices that the feed has changed, and give me a popup with a link to a page of your website with a brief summary of why I should be going there.. Feeds aren't entirely like radio, because a feed doesn't have to be 'seen in real time' for an interested user to get it in their aggregator.. {I use the Financial Times RSS aggregator (it's not one of the best) but it does a 'tickertape' accross the top of my desktop showing all 'current' stories}

RSS is one of a number of XML-over-HTTP syndication languages. If you can find a good potential use for that kind of technology, you'll know why it's of benefit.