A retirement plan is kind of like a savings account for grown-ups. It's money you put away for when you stop working. Your employer might have a retirement plan that helps you save some of your money to use when you're older. You could also set up a retirement plan of your own. To do that, you can put money in an account or buy something like stocks or mutual funds and the money you save will grow over the years. When you retire, the money you've put in these accounts will be there for you to use.