Short for 快速充电. Can refer to both the technology and the charger itself. Opposite: 慢充 (slow/standard charging). 无线快充 = wireless fast charging.
culture
Chinese phone brands compete aggressively on wattage: OPPO, Vivo, Xiaomi, and OnePlus have pushed 快充 specs to 240W+. The numbers (瓦, watts) are a big marketing battleground.