The picture on the far left is a typical AC mains transformer in a power supply and the waveform shows the AC waveform from it.
The voltage changes smoothly and rises to a value above the central (zero volts) line by the same amount as it falls below the line.
The oscilloscope's vertical (Y) amplifier is set to 5 volts/Div and there are just under three divisions from peak to peak - roughly 14 volts. The stated 10 volts output from the transformer is known as its rms value - the waveform's true peak to peak value is 1.4 times this, ie: 14 volts.