@Maria2704 I also do not understand your claim. According to the moderate cancellation policy, the guest should be refunded the cleaning fee and 50% of unused nights, as others have said.
https://www.airbnb.com/home/cancellation_policies#moderate
I use the strict policy on my more expensive listings, for this very reason.
And I have never heard of dates being blocked due to a guest cancellation (which would make no sense at all). The scenario you describe sounds more like a no-show, i.e. the guest doesn't cancel and doesn't appear. In that scenario, you would be paid in full and the dates would remain blocked.