Gerund used as an uncountable noun meaning the act or process of celebrating.
There was exuberant celebrating after the election results were announced.
После оглашения результатов выборов было бурное празднование.
celebratinggerund / present participle Present-participle adjective used attributively (e.g., "celebrating crowd").
The celebrating crowd filled the square.
Празднующая толпа заполнила площадь.