When we use a negative construction (with not) in the main clause, until means 'not before'. I won't (will not) start cooking until you come home. until three kilometres.
Medicare Part A is hospital insurance that covers inpatient hospital care and certain home care. Medicare Part A is usually free if you or your spouse paid Medicare taxes while working. If not, it can cost up to $413 each month in 2017. Hospital and skilled nursing facility stays come with deductibles and co-insurance.
This article explains Medicare Part A (hospital insurance). Medicare Part A is part of Original Medicare (along with Part B), the government-sponsored health insurance program for those who qualify by age, disability, or certain health conditions.