The kinetic energy of the emitted electrons is equal to the electron charge times the stopping voltage. We observe that there is no current flowing for small frequencies of light. This is because the electron requires a minimum energy to escape the surface of the anode. The higher the frequency of the beaming light, the higher the kinetic energy of the emitted electrons is. The kinetic energy plus the minimum energy is proportional to the frequency of the light.
All particles correspond to a wave.
It's a probability wave, whose square gives the probability of finding the particle at a specific position. The wavelength of the particle is inverse proportional to the momentum of the particle. The wave nature of electron is very prevalent in the electron microscopes. Since the wavelength of electron is much smaller than the light photons, we can observe finer details. An electron of an atom does not orbit the nucleus as the earth around the sun.