Bluedeb is correct that an AFLAC policy is not an HSA nor compatible with it.
HSAs are accounts that you can contribute to and draw from to pay medical expenses. To contribute to an HSA, you must have coverage from a High Deductible Health Plan (HDHP), and no conflicting coverage like Medicare or a regular health policy.
Although an HDHP does have limits on various aspects like coverage and out-of-pocket costs, there is more to an HDHP policy than just the limits, so I always encourage taxpayers to contact their insurance company to determine if the policy is an HDHP.
But to repeat, in your case, AFLAC is neither an HSA account nor an HDHP policy.