The IP address that's in the position of that red square is the IP address that your modem-router uses to connect to the outside world via your ISP. It's also not something that it matters one whit whether someone else sees or not.
The tests being performed aren't really for your computer to the outside world, as on virtually any wireless LAN or wired ethernet connection from a computer to a router you have throughput that's much faster than your internet service to the world, which is provided by your modem-router.
In my case my ISP is Verizon and the modem-router is a D-Link 2750. If I type 192.168.1.1 into the address of any web browser on my home network it will show me the main page of my modem-router's controls. One of the thing it shows is the connection address of the modem-router to the outside world, which matches exactly what is shown in the Speedtest screen. Speedtest can also generally tell who your ISP is based on the IP addresses that are assigned en masse for different ISPs to use (or at least I think that's the mechanism - I could be mistaken on that). This is shown in approximately the position of the black block you have above your red block. In my case it reads "Verizon Fios".
Edited by britechguy, 24 March 2017 - 10:26 PM.
Brian AKA Bri the Tech Guy (website in my user profile) - Windows 10 Home, 64-Bit, Version 1803, Build 17134
In a modern society where everyone thinks their opinion deserves to be heard nothing annoys me more than individuals who mistake their personal preferences for fact.
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