sb who has come back to China after gaining overseas experience (a pun on 海龜|海龟[hai3 gui1])
to return to China after a period of study or work overseas
Definitions (Wiktionary)
noun, neologism
haigui; an overseas returnee; one who has studied/lived overseas and returned to China
Examples (Wiktionary)
Mandarin
出国的，也有无数人做了中国第一代海归，捧着国外辛苦赚来的第一桶金，开始了国内的创业路。
出國的，也有無數人做了中國第一代海歸，捧着國外辛苦賺來的第一桶金，開始了國內的創業路。
chū guó de ， yě yǒu wú shù rén zuò le zhōng guó dì yī dài hǎi guī ， pěng zhe guó wài xīn kǔ zhuàn lái de dì － yī tǒng jīn ， kāi shǐ le guó nèi de chuàng yè lù ．
There are countless ones who became the first group of haigui among people that went abroad. Holding the initial profits they earned through hard work from foreign businesses, they started their businesses in China.