It means almost nothing... unless you get sick or run over by a car. My family skated by for years without health insurance. We even had two babies while uninsured. We lucked out and came out ahead. We saved far more by not paying insurance premiums than we paid on checkups, vaccinations and even the delivery of two babies. If my wife had to have a c-section or there were other complications things would have been quite different.
Edit: Also, if you just lost your insurance and you want continued coverage, look into COBRA coverage.