What is a Lens servo?

I want to buy a Nikon D5200.In nikon site I found this on specification Table. Lens Servo: Autofocus (AF): Single-servo AF (AF-S); continuous-servo AF (AF-C); auto AF-S/AF-C selection (AF-A); predictive focus tracking activated automatically according to subject status Manual focus (MF): Electronic rangefinder can be used.
Now please somebody explain me what is the lens servo.

All auto focus lenses from any manufacturer are, in effect, servos, in that they move the focus mechanism based on electrical signals from the camera.

Nikon (and Canon) use the term Servo to give the impression that their lenses are more powerful and faster to focus. It's a marketing ploy, another example of spin from the Ad guys.

With Nikon it's used to hide the fact that only their mid to pro range of cameras cameras have the auto focus motor built into the camera, you have to buy one with every lens if you want auto focus on their cheaper entry level models, which, of course, costs you more. Good scam eh!

It's basically the focusing motor. Those you quoted are different focusing modes you can use depending on whether you want auto-focus, are focusing on a still or moving subject or whether you want to focus manually.

Servo is an autofocus mode where the camera tracks a moving subject (eg sport or active kids) and keeps them in focus while you frame the shot.