Answer:
This quote comes from Julius Caesar. This metaphor refers to the fact that cowards "die" many times during their lives when they unnerve themselves in situations that generate fear.
When a person is a coward and does not face their problems or fears, those things stay with them inside them and it is what "kills them in life".
In contrast, it can be said that a brave person will live many times, since being brave and facing our problems is something that gives us a feeling that fills us with life.