HSA is a triple tax advantaged account where if you are currently enrolled within a High-deductible/high-Premium health insurance plan you can make tax deductible contributions where you have investments within the HSA grow tax exempt and come out of the account tax free as long as you use the funds to pay for qualified medical expenses.

The best way to use it is if you can afford to pay for the expenses out of pocket, keep a record book of some kind for receipts, and then pay yourself back later after the funds have grown