godan verb (-ru), intransitive verb
act happy; show gladness; be visibly pleased
Describes someone outwardly showing happiness or excitement, often from a third-person perspective. The がる suffix adds a sense of 'appearing to feel' or 'acting as if'.
彼女はプレゼントをもらって嬉しがっている。
She is acting happy after receiving the present.
子供たちは遠足の話を嬉しがって話した。
The children talked excitedly about the field trip.