Once upon a time, there were two ways to send humans to the ISS, the only permanently manned space station: the American Space Shuttle and the Russian Soyuz. Then the Shuttle program ended, meaning that the only way for *anyone* to get to space (including, sadly, Americans) was on board the Russian Soyuz (the Chinese Shenzou can be safely disregarded for the time being).
Then, a few days back, one of the Soyuz rockets went KERSPLAT, shutting down launches of Soyuz for the time being until the problem can be resolved. This leaves the crew currently onboard the ISS with no schedule for replacement. They are all stocked up on supplies, so there are no worries there… but they do have two problems: limited on-orbit lifetime for the Soyuz spacecraft (basically, the seals in the propulsion system have a shelf life while in the vacuum of space) and the fact that winter in central Asia sucks.
There are currently two Soyuz’ connected to the ISS. The older one’s warrantee expires in October, and it *will* be coming home by then, bringing half of the crew. This leaves three with the last Soyuz. And they need to land in daylight. And in central Kazakhstan, that means getting down by November 19.
So after a bit less than a dozen years of mankind never leaving the foothold of outer space unmanned… unless the Russians can pull it out, figure out what the Soyuz problems are and get them flying again, we may soon see humanity retreat from space.