When a landlord marks their property as reserved, it means that they are closing off new inquiries in their inbox.
You can only see a reserved property if you have already contacted the landlord. This also means that new peroperty seekers can no longer contact the landlord.
This often indicates that the landlord is in the process of selecting their new tenant from the messages. If you have already contacted the landlord, you will still be able to maintain a dialogue with them.
Once the landlord has found a tenant, the property will be marked as rented. If you are not the fortunate tenant, it will no longer be possible to message the landlord.