There are closed funds, front end, rear end, and no load funds, fees, hidden fees, this is only a partial list of things to consider. The money for the each group is invested by a professional manager. In this way the investor doesn't have to decide when to buy or sell. Mutual funds depending upon their objectives, can include equities like stocks, bonds, cash or cash equivalents like treasury bills. The value of the mutual funds change from day to day, depending upon economic conditions, market or company news, interest rates and so on.
Mutual funds vary in their risk, from low risk to high risk.
The risk depends in which pool or fund the money is invested in. Worthwhile reading, to obtain a more through understanding what or where the money is invested. In this way different investing styles are possible, from low risk to high risk. Relieving you of the problems when to buy or sell and what. Any dividends or capital gains go to buy more shares in the fund, unless you direct them to do otherwise.