红包(hóng bāo) - red envelope, red packet in Mandarin

红包 (hóngbāo) is a "red envelope" or "red packet": 红 (hóng) means "red" and 包 (bāo) means "packet, bag, wrapper". It almost always contains money, given as a gift at Chinese New Year, weddings and birthdays.

At 春节 (Chūnjié), married adults and grandparents give 红包 (hóngbāo) to children and unmarried younger relatives. The amount matters less than the gesture, and the red colour of the envelope is meant to carry good luck rather than the cash itself. You will also see the phrase 发红包 (fā hóngbāo), "to hand out red envelopes", and the modern twist: digital 红包 (hóngbāo) sent through mobile payment apps at festivals.

Numbers matter here: amounts ending in 8 (八, bā) are popular because it sounds like 发 (fā), "to prosper", while 4 (四, sì) is avoided because it sounds like 死 (sǐ), "death".