Plenty of useful information on the Volleyball England site concerning this initiative aimed at children aged 7-11
See link here: https://www.volleyballengland.org/news/article/6248/volley2s-our-new-national-programme
It is an adapted 2v2 version of the game and helps to gradually develop volleyball fundamentals by taking players through four key stages: Red, Amber, Green, and Gold. The article includes a link to download a free detailed guide on Volley2s.