It's blood poisioning, but if it's treated quickly there's a good chance of recovery. It can be very dangerous but it really depends exactly what's wrong. Don't worry, he's in the best place and I'm sure he'll be fine
As a condition it can range from reasonably treatable (in hospital) to a very severe condition.
I don't think that it is a good idea for you to google etc because you could end up worrying yourself more than you need. It is a much better idea to try and get hold of your parents to see what exactly is going on.