Beneficent describes a person, an act, or a power that helps people or leads to something good. A beneficent donor, a beneficent law, a beneficent god. It is formal and a little literary. In speech, kind or generous is what most people say. Though actually, beneficent is stronger than “nice”: it points to help that does real good, not only a pleasant manner. Do not mix it up with beneficial. Beneficial is about a good effect (exercise is beneficial to your health). Beneficent is about a good-doing character or act (a beneficent ruler). One is “having a good result”; the other is “doing good.”