Formula Wave in Vacuum Phase velocity    Frequency    Wavelength

Phase velocity

Unit
Phase velocity is the speed of propagation of the same phase of a (monochromatic) wave.

In the case of electromagnetic waves, the phase velocity is the speed of light: $$c = \lambda \, f$$, with the value $$c = 299 \, 792 \, 458 \, \frac{\mathrm m}{\mathrm s}$$.

Frequency

Unit
Frequency of the wave. Indicates how often the wave (e.g. light wave) oscillates per second.

Wavelength

Unit
Wavelength is the smallest distance between two points of the same phase. For example, the distance between two wave crests.