Cash makes the world go round.
You need cash to make cash, as unfortunately no-one has yet found a tree from which we can go and pluck 20 notes at will. Companies raise cash in various different ways, either though bank loans, a myriad of novel debt offerings, venture capital funds, or through a public offering of shares. Think of how you would go about opening the corner store that you've so longed for over the years. Large companies think in exactly the same way, although on a much bigger scale. Companies live and die on the amount of cash they generate.