Here "good shepherd" is a metaphor that represents Jesus. AT: "I am like a good shepherd" (See: [[rc://en/ta/man/translate/figs-metaphor]])
# lays down his life
To lay down something means to give up control of it. It is a mild way to refer to dying. AT: "dies" (See: [[rc://en/ta/man/translate/figs-euphemism]])