That number is the IP address for the person who viewed your item. It stands for Internet Protocol.
"Every machine on a network has a unique identifier. Just as you would address a letter to send in the mail, computers use the unique identifier to send data to specific computers on a network. Most networks today, including all computers on the Internet, use the TCP/IP protocol as the standard for how to communicate on the network. In the TCP/IP protocol, the unique identifier for a computer is called its IP address."
"In Microsoft Windows, you can enter ipconfig in the command prompt app to view your computer's current IP address configuration."
It's just the address of the computer used by the person who viewed your item. I hope this helps.
Sandra