Mutual funds are basically where people pool their money in order to buy stocks. This is more efficient than trying to guess and buy stocks yourself, as you save on fees, commissions, and you pay a professional to pick the stocks.
Some mutual funds do great, others do poorly, and there is no guarantee as to which fund you will pick. Additionally, mutual funds have to pay the professional gambler that picks the stocks.
The advice I like is to stick with index funds. An index fund follows one of the major stock indices (Dow Jones, Russell 2000 Index, etc.). You know exactly how your fund is doing just by watching the stock index. They also have lower fees, as there isn't anyone picking stocks.
This is what I've learned from dipping my toe in the investment waters. Here's the best plan for getting rich I've ever heard (From Scott Adams, author of Dilbert;
'Dilbert' deserves the economics Nobel:
1. Make a will
2. Pay off your credit cards
3. Get term life insurance if you have a family to support
4. Fund your 401k to the maximum
5. Fund your IRA to the maximum
6. Buy a house if you want to live in a house and can afford it
7. Put six months worth of expenses in a money-market account
8. Take whatever money is left over and invest 70% in a stock index fund and 30% in a bond fund through any discount broker and never touch it until retirement
9. If any of this confuses you, or you have something special going on (retirement, college planning, tax issues), hire a fee-based financial planner, not one who charges a percentage of your portfolio
Personally, I might move "buy a house" up on the list, provided you know you will stay in the same place at least 5-7 years.