In theory, The ability to recognize the perspective of a counterpart and the vocalization of that recognition. In practice, paying attention to another human being, asking what they are feeling, and making a commitment to understanding their world
Empathy doesn't necessarily mean sympathy (feeling the same thing) or affection. "No hugs", as Chris Voss puts it in Never Split the Difference.
Hence, an amoral or even wickedly psychopathic person can achieve empathy; proverbially evil intelligence agency interrogators can deploy it as a weapon