@Ramon49, if the host does the cancellation, then the dates on the calendar will be blocked and the host will have significant penalties applied.
(No superhost, automatic bad review, guests will be scared off, lower search rankings, etc.)
In the future, if the guest wants to cancel, the guest must do the cancellation. Always.
On AirBnB, the host should never do the cancellation unless the host has an unavoidable reason of their own to want the cancellation to happen.
If you are a new host and you did not know this, you can try to contact AirBnB directly and explain that you did not know what you were doing. They may or may not unblock the days for you, but asking AirBnB is definitely the only to get your calendar unblocked.