>>13843814
The point is to put your money into a fund that reflects the stock market as a whole, not bet on a small group of stocks that you hand-picked, because you can't know which stocks will underperform and which will excel. So you invest in mutual funds that mirror a broad market index, like the S&P 500. You pay a company, the company buys a bunch of stocks to get a portfolio that mirrors the overall market, and you get a cut of the returns.
And you put some money into a similar bond fund, because when the stock market slumps, the bond market generally surges, and vice versa.