How to understand the special purpose company?

For example, China citizen A invested 654.38 billion yuan to set up Company A in China and acquire Company B in the United States. In order to achieve the purpose of financing, A bought the shares issued by American Company B with the shares held by A as an investment means (equivalent to exchanging the shares held by A with the shares held by American Company B, then American Company B owns a large number of shares of China Company A), and Company B applied for listing according to American law, which essentially realized the purpose of listing the shares of China Company A in the United States through American Company B, so Company B was called a special purpose company.