I saw it there too, I went to check afterwards. note this is a boring subject read at your own risk
IPO = Initial Public Offering
I will answer your question with an example.
Company A is a CPU making company. They figured out how to make CPUs that go 100 speed. Other companies only know how to make CPUs that go 10 speed. So, Company A is the only company that knows how to make CPUs 100 speed and for ever this will be true.
Company A makes 100 bitcoins every year because they sell 100 CPUs for 1 bitcoin per CPU, and only 100 per year. Company A spends 10 bitcoins per year to run the company. So Company A earns 90 bitcoins profit each year.
Owner of Company A wants to retire and do something else. Owner has owned Company A for 10 years and everyone know Company A is the best, and forever this will be true that Company A will earn 90 bitcoins profit.
Owner wants to do something else with more than 90 bitcoins per year, Owner wants to do something else. Owner knows he must wait a long time to earn more bitcoins Owner wants to do something else and Owner wants 9000 bitcoins, that’s going to take 100 years!
So Owner tells everyone else, that if Owner gets 9000 bitcoins Owner will give up Owner and let someone else be Owner to earn 90 bitcoins each year and be Owner of Company A.
Company B has 4500 Bitcoins, and can never die. Crowd A is 45 people with 100 bitcoins each. Company B offers to Owner 4500 bitcoins for 50%. and Crowd A offers all of their bitcoins each totalling 4500.
Company B is 50% Owner and Crowd A is 50% owner.
Original Owner gets 9000 bitcoins walks away gives up Company A to Company B and Crowd A and does something elsevand lives Original Owner life, (or makes new CPUs that go 200 speed, but that’s a different story)
Company B now as 50% owner earns 45 bitcoins per year, and Crowd A each person earns their own piece, which is 45 people so each earns 1 bitcoin per year.
In 100 years 45 people will each earn 100 bitcoins and Company B will earn 4500 bitcoins and Both Crowd A and Company B still own Company A.
Company A’s value is based on the fact that it always earns 90 bitcoins after spending 10 bitcoins, which means Company A’s stock value goes up because of the amount of unspent bitcoins it earns. The company can pay a dividend(the profits) to the owners, or keep the bitcoins in the Company A wallet and make the stock price go up in price.
So, if you buy IPO the company has to have some kind of value, some kind of earnings amount, some kind of reserve of items, which will back up the shares of that company.
The above example is an ideal world; and this is usually not how things happen.