We can understand classical gravitational waves as small perturbations moving in a background spacetime. In this picture, a gravitational wave is very similar to an electromagnetic wave. A general configuration of gravitational waves is a superposition of plane waves with different frequencies, wave vectors, and amplitudes. The frequency and amplitude of a gravitational wave can be measured by its effect on freely falling test masses, such as the mirrors in an interferometer like LIGO or Virgo.
A graviton is a quantized fluctuation in the gravitational field, much like a photon is a quantized fluctuation in the electromagnetic field. Again, we can understand many of the properties of gravitons by direct analogy to photons. A graviton (like a photon) has a frequency $f$, but not an amplitude per se. A graviton carries energy, which is related to its frequency by $E=hf$, where $h$ is Planck's constant.
As @annav points out in the comments, one has to be a little careful with interpreting the frequency of a photon, since a photon is not a classical wave. Ultimately, this is related to the wave-particle duality. In some circumstances, a photon behaves like a wave, and in others, like a particle. In circumstances where we can treat a photon as a wave, then it has a frequency $f$. You can also understand the frequency of a photon by building a coherent state of many photons with the same frequency and a coherent phase; then you will build up a classical electromagnetic wave that has that same frequency in the ordinary, classical sense.
While the formalism of quantum field theory is clear about what properties a graviton should have (at least at sufficiently low energies), one difference between gravitons and photons is that gravitons have not been detected and there is very little chance we will see one detected in our lifetimes; in fact it is debatable whether a single graviton is detectable even in principle.
