Yes.
I suggest you pick a random high numbered port (10000 - 65500) and use that as the external port. Then the internal port number is whatever you have
Blue Iris listening on (usually 80 or 81) and the local address would be your Blue Iris PC's IP address (usually 192.168.x.xxx).
Of course every router's port forwarding interface and terminology is different but hopefully you can figure out what is what.