Okay, I think this can be explained somehow, but I don't remember how.
Imagine two persons: one inside a train, and one outside of the train.
The train moves at 30 mph, the person inside the train walks at 5 mph.
From the other persons point of view, the person inside the train is moving at 35 mph.
Now imagine a spaceship moving at 0.6C (60% of the speed of light). Another spaceship is heading the opposite direction at 0.6C. From both spaceships point of views, the other spaceship is moving away from them at 1.2C. That means that the spaceships (seem to) move faster than light.