The graph is periodical meaning that it repeats itself after some point. This is because the motion of the wheel makes the car move up and then come back down again. Each local min point is likely where the riders get on the ride, since its closest to the ground. Each local max point is the highest point on the graph indicating when the car is at the top of the wheel.
Let's say that the vertical distance from the lowest point to the highest point is 50 feet, just as an example. This would mean the amplitude is half that at 50/2 = 25 feet. The amplitude represents the vertical distance from the center line to either the highest or lowest point.
The period describes how long each cycle takes. For instance, if it takes 60 seconds for a specific car to go from the bottom position, loop around, and then come back to the bottom position, then the period is 60 seconds. The frequency is simply 1 over the period. Though the frequency may not be used as much.
So overall this curve is likely a sine or cosine curve (depending on the phase shift of course). Also there's a vertical shift as well. Because we don't have any numbers to work with, the actual sine or cosine function cannot be determined.
