What did Herodias' daughter do at Herod's birthday that pleased him?

Answer: She danced

On Herod's birthday the daughter of Herodias danced before the guests and pleased Herod, so he promised her whatever she asked.

“On Herod’s birthday, however, the daughter of Herodias danced before them and pleased Herod so much that he promised with an oath to give to her whatever she asked.”— Matthew 14:6-7 (BSB)