painful and stressful

These two words mean basically the same thing and emphasize how difficult the person's work is. (See: rc://en/ta/man/jit/figs-doublet)

his soul does not find rest

Here man's mind is referred to as his "soul" to emphasize his deep thoughts. Alternate translation: "his mind does not rest" or "he continues to worry" (See: rc://en/ta/man/jit/figs-idiom and rc://en/ta/man/jit/figs-metonymy)