It typically gives you payouts if you wind up having cognitive impairment - such as dementia or Alzheimer's - or if you physically can no longer perform some specific "activities of daily living" on your own. We're talking about feeding yourself, bathing yourself and so on.
Payouts from the policy will help cover the cost of assistance to help you get through the basics of daily life. For example, the policy can pay for someone who stops by the house for a few hours a day or a few days a week. Or it can help with the cost of a senior day-care facility, an assisted-care setup or full-fledged nursing-home care.