delighted, pleased
忭 centers on a feeling of joyful satisfaction: being delighted or pleased.
忭 combines the heart radical 忄 with 卞, which likely contributes the sound. The exact historical development is uncertain, but the structure suggests a phono-semantic compound where the heart component relates to emotions.
The heart radical 忄 beside 卞 suggests a heart that is light and uplifted. Picture a heart doing a little joyful jump: 忭 is the feeling of being delighted.
For ヘン, imagine a hen clucking happily in a sunny yard: hen -> ヘン, and the hen's cheerful mood matches the delighted feeling of 忭.