distinction between right and wrong; distinction between good and bad
Refers to the ability or act of telling right from wrong, or good from bad, often in a moral or ethical context.
It is a parent's duty to teach children the difference between right and wrong.
He cannot tell right from wrong.
善悪 means 'good and evil' or 'right and wrong' as a concept, while 善悪の区別 specifically refers to the distinction or ability to differentiate between them.
Compound of 善悪 (good and evil) + の (possessive particle) + 区別 (distinction). The phrase is straightforward and its meaning is transparent from its components.