I want to get to the end of the metaethics sequence before pontificating too much, but I'll say a little.

What is yummy? A sense of taste, an evaluation of a particular sensory modality which impels action - eat more.

What is scary? Well, also an evaluation, but not confined to a particular sensory modality. It's an evaluation of threat, a fairly complex evaluation, and it impels action too - fight or flight.

What is moral? The moral sense also evaluates - it evaluates the actions and attitudes of people, and it also impels action - attitudes and reward or punishment, for actions, for attitudes about actions, for properly rewarding/punishing actions, for properly rewarding/punishing attitudes about actions, ...