One definition of conscience states:
"An (inner feeling or voice) viewed as acting as a guide to the rightness or wrongness of one's behavior." I tend to agree with that.
Professional accomplishments can be had by one of immoral values and shady practices. A conscience is that voice that tells you that you need to apologize for your actions when you are wrong.
It also can be an inner voice of praise that comes with knowing you did right by someone.
Ultimately it is a (feeling)/thoughts of our actions within the context of what's right/wrong or fair. Do we feel good or guilty about our actions?
In order to develop a "healthy conscience" it usually starts in our early childhood with her parents, teachers, and ministers teaching us "right from wrong" along with learning to have "empathy" for others.
A psychopath is usually seen as being devoid of a conscience. He or feels no guilt or remorse for causing others pain. There is no empathy or compassion component to their reasoning. It's all about their ego.
A win at any cost is a win. "The end justifies the means" is their motto.