It's a company that goes public (trades on a stock exchange) with no actual business. It sells new shares (traditionally for $10 each) to investors, creates a p

It's a company that goes public (trades on a stock exchange) with no actual business. It sells new shares (traditionally for $10 each) to investors, creates a pot of money (the size needed determines the number of shares sold) and promises a business model of "acquire [existing thing]". It then has some amount of time to set up the acquisition and get the shareholders to approve it. If it doesn't, the $10/share (plus interest) is returned to them. The thing being acquired gets to go public without needing an IPO. The people who buy the SPAC end up owning shares of the thing.