It involves taking out a policy that covers both your outbound and return trip.It also includes your vehicle in case of an accident or malfunction. You can consult the conditions here.
The amount of the insurance is 4% of the cost of the ticket after applying service charges and discounts. You'll need to take out the insurance before the reservation is confirmed and paid.
The company you'll take out the insurance with is ERGO. You must direct your reimbursement claim to them in case of cancellation (you'll find all the information you need in the policy you receive with your ticket).