What does it mean when Want Want Group hires the fourth class?

Recruiting four people. Want Want Group was formerly known as Yilan Food Industry Co., Ltd. He founded the Want Want brand in 1983 and went to mainland China to invest and set up factories in the early 1990s. After years of development, Wangwang's footprints have spread to 61 countries and regions in Asia, Africa, North America, Central and South America, Oceania, and Europe. When Want Want Group needs to recruit people, it will put up a sign at the entrance of the company saying hire 4, which means recruiting four people.