How does Public Mutual fund work? A guy at work wants me to get in on it, but I'm not sure.

If I put in say 10k into a mutual fund account, the bank will buy some shares in certain industries for me, and hopefully the price per share will go up after a few years/10 years?

What then? How do I sell the shares I have? Can I just go to the bank and say "hey I don't want my account anymore, please give me all my money", and I'll get the all the money + the interests I've earned right away?