noun, noun or participle which takes 'suru'
birthday party; birthday get-together
A gathering to celebrate someone's birthday, often with food, drinks, and activities. Can be used as a noun or with する to mean 'to hold a birthday party'.
友達の誕生日会をレストランで開いた。
We held a birthday party for our friend at a restaurant.
来週、彼女
We're planning to have a birthday party for her next week.