A mutual fund is a company that combines, or pools, investor's money and uses that money to buy stocks or bonds. Each day the accounting staff of a fund adds up the value of all the securities in their portfolio, plus other assets like cash, then deducts liabilities. Then they divide the net assets by the number of shares outstanding. This is the NAV or net asset value of each share in their fund.
Some funds have what is called a load.
This is simply a sales charge for you doing business with them. A no load fund has no sales charge, although most funds do charge a very small administration fee. All mutual funds are required by law to provide info about their fund to prospective investors. This info is called a prospectus. This describes all about the fund itself, the fund's objectives, costs, and securities they invest in.