This graph depicts a waveform known as a sine wave. It shows a series of regularly spaced, alternating peaks and troughs. The line graph has the Y axis labelled as voltage and the X axis labelled as time. There is no scale indicated on either axis. The peaks are above the X axis and are all at the same height. The troughs are all below the X axis and are the same depth.
The line graph starts at the point where the X axis meets the Y axis and rises smoothly to a rounded peak. The line then drops smoothly down to a rounded trough the same distance below the X axis. Then it rises again to the next peak, which is the same height as the previous peak, then drops again to a trough of the same depth. This continues for three cycles in total.
The vertical distance from a peak to the X axis is labelled as amplitude. The horizontal distance between peaks is labelled as one cycle.