She might be confusing things. Overall the company can only spend 20% on overhead etc.
But an actuarial value at the plan level, say of 70% (silver plan), means that for a standard population, the plan will pay 70% of their health care expenses, while the enrollees themselves will pay 30% through some combination of deductibles, copays, and coinsurance.
60% would be bronze, 70% silver, 80% gold, 90% platinum. Then there are also the 73%, 87%, and 94% silver plans if you have copay assistance based on income.
So one meaning has to do with the company expenses in aggregate and overhead. The other relates what % the insurance companies will pay in relation to how much individuals will pay on average of their expected annual health care expenses in out of pocket amounts.