When you configure an ACL for an access profile, in this case - the SSH access profile, there is an implicit deny entry. This means, other than the traffic explicitly allowed (10.10.10.252/32), all other SSH access will be denied.
1. Source-address is where the traffic originating from, like a end user/device (host).
2. Destination-address is where the user traffic destined to communicate (send the data to an end point).