There are a couple of different ways to fly. One of them is Visual Flight Rules VFR. When I fly my small plane for fun, that is how I fly most of the time. A pilot under VFR can choose their own route. They are not required to be in communication with ATC until they approach an airport. You can navigate based on looking out the window, using a magnetic compass, and a paper map. You can fly like they did in 1950 if you want. Although most pilots use a GPS navigation system.
If you fly in bad weather or are flying an airliner, you will likely be flying Instrument Flight Rules IFR. This kind of flying requires you to fly based on a specific clearance. It is probably a specific route between designated GPS waypoints. Sometimes they just tell you to fly directly to where you are going, that is nice.
For IFR, there is a system of routes called “Victor Airways”. These are a way to link a number of different points together into a long chain. It allows a much quicker description of where you are supposed to go. It is like saying: “get on highway 280 at the Woodside Road exit, don’t get off until you get to San Jose”….
I paste in a picture below of the screen of my GPS navigation system. This is an old unit, but it works very well. Newer equipment has larger screens, lots of features. I have set up a series of way points. I just passed “santy”. This is near Santa Cruz, and I am heading out over beautiful Monterey Bay, California. The bottom photo is what I might see out the window looking towards Monterey.