Answer:
"Courage is Grace under fire" means to be able to be calm when most people would be panicking. A soldier that is caught in enemy crossfire that manages to remain calm and get out of the crossfire alive is a good example. Another example might be a famous person being questioned by the public on a topic/subject that he might not want to talk about, but he talks about it anyway and remains calm.
Courage is grace under fire is just saying that to remain calm in one of those situations takes courage.
Best wishes!
