"RSS" is about getting live web feeds directly to your computer. RSS takes the latest headlines from different web sites, and pushes those headlines down to your computer for quick scanning.
The acronym RSS stands for Really Simple Syndication.
In each of the above meanings, the purpose is the same: to have web sites of your choice deliver their latest news directly to your monitor. So instead of having to visit 14 different places to get your weather, sports, favorite photos, latest gossip, or latest political debates, you just go to one screen and see it combined ("aggregated") into a single window.
The RSS headlines and stories are effectively immediate. Once published at the source server, RSS headlines take only moments to get to your screen.