If your service provider is Verizon ... and you run the test from a Verizon web page ... Verizon might "fast path" traffic that starts and ends on the Verizon infrastructure backbone.
The more network "hops", the more different network routers, switches, etc., your network traffic traverses.
Think of a service provider as an airline.
Think of a network as a flight.
Think of flight itinerary as a route.
Some service providers "fast path" traffic that doesn't leave their network - a direct flight, no stop-overs.
Accessing a site outside the Verizon network is like 1-stop, 2-stop, or 3-stop flight. The layover is "latency". The more layovers on your itinerary, the more time it takes to reach your destination.
Computer networks and airline networks are similar in design, but one uses airplanes and the other uses bits, bytes, and packets.
Where you go, how you get there, and how long it takes will vary for the same reason some flight intineraries take longer than others.