Deleting not existing records via SSH

Hi, i deligated a domain to the Nameserver of dynv6. Before i added any record, i deleted via SSH a record type of a subdomain:

first i looked for records:
$ ssh “hosts domain.tld records”

Then i deleted the subdomain test
$ ssh “hosts domain.tld records del test a”
21 records deleted

And there were 21 records been deleted…? Where does this number came from? Do i delete anything, or is this just a number coming anywhere, and returnes it?

Have a nice day