en_tn/pro/15/13.md

A joyful heart makes the face cheerful

Here the word "heart" represents the person. Alternate translation: "When a person is joyful, his face is cheerful" (See: rc://en/ta/man/jit/figs-synecdoche)

by an injured heart the spirit is broken

The writer speaks of a person being discouraged as if that person's spirit were an object that is broken. Possible meanings are 1) The "injured heart" is spoken of as if it were a person who broke the spirit or 2) a person whose heart has been injured will also be discouraged. This can be translated in active form. Alternate translation: "an injured heart makes a person become discouraged" (See: rc://en/ta/man/jit/figs-metaphor and rc://en/ta/man/jit/figs-activepassive)