It means that your computer is on a private network which performs NAT between the private network and the Internet.
NAT is a method to deal with the shortage of IP addresses. Your company might have 100 computers, but only 1 IP address on the Internet (a "public IP address" or "external IP address", in more technical jargon). The way this is handled is the private network at your work gives all the computers a private IP address (usually
192.168.*.*), and then the router that manages the network "translates" these IP address back and forth from the 1 Internet IP address when the work computers try to access the Internet.