This is a popular saying which means 'he who kills by the sword, dies by the sword', indicating that one's actions will have consequences of the same nature.
Examples
- Spanish: Roberto siempre fue violento con los demás, pero el que a hierro mata a hierro muere. Ahora está en la cárcel por asalto.
- English: Roberto was always violent towards others, but he who kills by the sword, dies by the sword. Now he is in jail for assault.