E-commerce / retail term that went mainstream with the rise of Taobao and livestream shopping in the 2010s. Common on shop banners, app notifications, and live-selling stream titles: 新品上新, 每周上新.
memory
上 here means 'to put up (online / on the shelf)' — the same 上 as in 上架 (put on the shelves) and 上线 (go online). 上 + 新 = 'put up [the] new'.