What exactly does a saint in Europe mean?

The European saint refers to the little girl named Joan of Arc.

During the Third Hundred Years' War between Britain and France, the British army occupied almost the whole of France. At this time, Joan, a girl of 17 years old, organized the French people's guerrillas to resist the British army and finally defeated them.

But then Joan was betrayed, taken to England and burned by the church. The French people called her a saint.