I do not know how this exactly works. I hear that in the US you can buy fractions of the stocks. For instance if the price of stock is $800, you can buy 25 percent of the stock or $200 worth of that stock.
Stock splits and reverse stock splits are corporate actions that affect the number of shares outstanding for a particular stock. They are typically undertaken by companies to adjust the share price and make it more accessible to investors or to meet certain listing requirements.