You should open an IRA (Individual Retirement Account). The reason to open this kind of account is because they come with tax benefits, which an account somewhere like Robinhood won't

There are two kinds of IRAs: Traditional and Roth.

For Roth, your deposits to it are NOT tax-deductible now when you make the money (unless you have income that is pretty low). But you then don't have to pay any taxes on the money or your gains when you take it out in retirement.

For Traditional, your deposits to it ARE tax-deductible and you won't have to pay taxes on it now, but you DO have to pay taxes on the money and your gains when you take it out in retirement.

Which one is "right" for your situation can be overwhelming and difficult to figure out. But the most important thing is to open an IRA, NOT a taxed brokerage account somewhere like Robinhood.

Check out places like Schwab, Fidelity, Vanguard, and TD Ameritrade which I believe are all highly recommended by this sub generally. You can do it all online too!