Health Savings Accounts offer a triple tax advantage

If you have a high deductible medical insurance you can contribute to a triple tax free HSA.
1. no federal income tax owed on contributions.
2. balance grows tax-free
3. withdrawals for qualified medical expenses are tax-free
Fidelity offers an excellent summary of the benefits of Health Savings Accounts (HSAs) at https://www.fidelity.com/viewpoints/personal-finance/hsa-healthy-habits
"HSAs offer a number of benefits: not only spending for the short term, but also saving for longer-term qualified medical expenses, including those in retirement." Enjoy a triple tax advantage!
Also: How your health savings account can be a powerful retirement tool:
https://www.fidelity.com/insights/retirement/hsas-in-retirement-infographic
How to get the most out of your HSA: https://www.fidelity.com/insights/personal-finance/getting-your-hsa-in-shape-infographic
Your investment choices include mutual funds, self-directed brokerage accounts, CDs, and savings accounts. Employer-sponsored HSAs may limit your investment/savings choices but individuals buying an HSA on their own can choose from a wide variety of providers. To find an HSA check: https://www.hsasearch.com/
If you have an HSA with your current employer but are leaving that job, or if you are retired, you can move your HSA funds to another provider.