The /32 is called CIDR notation.
http://en.wikipedia.org/wiki/Classle...Domain_Routing
/32 means that 32 bits of the IP address never change. And since an IPV4 address is only 32 bits, then that means it's a single IP address.
For example, on my internal network, I have it set up as 10.0.0.0/8, which means the only thing in the IP that ever stays the same is the first octet (the "10."). So I have over 16 million IP's available on my internal network.
As far as "port forwarding" to the jail, you'll have to do that at your switch/router level. Since the jail has its' own IP address, you can forward all requests on port 80 from your router to the IP of the jail (assuming, of course, that the jail's IP sits on the same subnet as your router). If the rest of your "internal" network is, for example, 192.168.1.0/24, then this solution won't work (since 10.10.10.100/32 is not in the same subnet).
Hopefully I didn't confuse you further
