The number of channels is the number of functions on the plane. Each thing like rudder, elevator, throttle, flaps, ailerons, retractable gear is a channel. The servos are the little motors that drive each function or movable surface of the plane. The receiver is what the servos plug into. There is also a switch harness to turn it on and off and a receiver battery. The transmitter is what controls the receiver and servos.

The plane you are looking at has 3 channels. Rudder, elevator and throttle. It comes with a 3 ch radio which will be very limited with your next bird. If you are going to stick with the hobby, I would look at a 40 size trainer like the eagle II or something similar and a .40 motor and a good 4 to 7 ch radio so you can use it later. If it is just something you want to play with for a week and then throw away, go for the one you are looking at.

There are a lot of ways to get into the hobby. Personally, I don't think the plane you are looking at is the right one, but like I said, if it is just something you are going to do short term, it is fine. Don't fly it in a lot of wind. They don't take much.

Good luck in what ever you choose. You may want to find the closest club and go out and watch what the guys are flying and ask questions. You may realize it is something you want to do all the way and get good equipt the first time so you don't have to replace it all when you get a new plane. The park flyers are ok short term, but they become boring very fast.

Have fun.