Normally oscilloscope represents the voltage waveforms. Typically, horizontal axis (X-axis) represents the time while vertical axis (Y-axis) represents the variation of magnitude of applied voltage signal with respect to time.
Magnitude of voltage and time period of the applied waveform can be calculated as follows.
Peak to peak voltage = number of vertical units × (volts/division)
Time period = number of horizontal units per cycle × (time/division)