Ebola is a virus, and has no ability to do things by itself, it can only survive by infecting things. We try to fight this infection with our immune system.
Usually this is done with Dendritic cells, but in the case if Ebola, the immune system is directly attacked. The virus takes over the dentritic cells and disables their protective mechanisms enabling the virus to multiply rapidly.
As Ebola spreads, it leads to dehydration, widespread internal bleeding and organ failure.
Other symptoms include, nausea, vomiting and chest pain.
In 6 out of 10 cases, Ebola is fatal. However! Despite the excessive media coverage and panic, it is important to remember that Ebola can only be caught through the exchange of bodily fluids with someone contaminated by the virus... Or contact with an infected bat. So infection is actually very unlikely.