Peak-to-peak voltage (Vpp) can be explained in terms of a sinusoidal-waveform voltage. Peak-to-peak voltage is a parameter measured between the maximum signal amplitude value and its minimum value (which can be negative, as in this case) over a single period (Fig. 1).
With a maximum value of 5 V, and a minimum value of -5 V, the peak-to-peak voltage is 10 V.
A similar parameter used in electronics is often mistaken for the peak-to-peak voltage, i.e. peak voltage denoted as Vp. Peak voltage (Vp) is measured from 0 to the maximum value (5V in the example). For a sinusoidal-waveform signal, Vpp will always be twice the Vp.