Actual cash value equals the purchase price of your car minus depreciation and your deductible. So comprehensive coverage will pay an amount up to the actual cash value of your car to either repair or (in the case of a total loss) replace it. If the cost of repairs exceeds your car's ACV, your car insurance company will declare it a total loss and pay the sum of the car's ACV to help you replace it — unless you opt to retain salvage (i.e., keep the totaled car), in which case the salvage value will also be deducted from your payout.
When you purchase comprehensive coverage, you will select a set deductible, which is the amount you pay out of pocket toward a covered claim. Let's say you choose a $500 deductible, and your car is later damaged by hail in a covered claim. If it costs $1,500 to repair your car, you would pay your $500 deductible, and your insurance would pay the remaining $1,000.