The HSA qualified health plans are full health insurance plans but they have a high deductible - you pay for the first so many $$ of health care you use, then the insurance kicks in, usually at a 100% rate.
I have a single plan with a $2600 deductible - I'm responsible for the first $2600 of my medical expenses every year. I stuff $2600 a year into the accompanying HSA account, and use that, tax-free, to may the charges that apply under the deductible.
Unfortunately, it looks like my state does not allow HSA's.