A PTR record is a pointer record for reverse lookup for DNS. It is used to find a host name by using an IP address. On windows 2000/XP you can use nslookup to test it. The fact that there is only one is probably because you haven't set any host records up, or if you have you didn't tell them to create a PTR record as well. So the one that is there should be the IP address of the server running DNS.
1.168.192.in.addr-arpa represents the network you are on which as sirdice has said looks to be 192.168.1.0 with a subnet mask of 255.255.255.0

Greg