What is the relationship between mass and frequency?

Hint: Mass and frequencies are two different quantities, they measure a different thing. So, they are not always related to each other. But here, let us consider the mass-spring system and try to figure out the relation between mass and frequency.

Complete answer:
Mass can be understood by the fact that the higher the mass higher will be the force required to make it move. Similarly, for frequency, we can say that if we want the frequency to be high then the energy given to move the object will be high.
For a spring-mass system, the frequency and mass can be defined as, when the mass has increased the frequency will decrease and when the mass has decreased the frequency will increase.
$ \Rightarrow f \propto \dfrac{1}{m}$
Here, $f$ is the frequency and $m$ is the mass.
Hence, the mass and frequency are inversely proportional to each other.

Note:
Mass and frequency are not always related to each other hence it is important to know about what context we are talking about. For example, the mass of the pendulum has nothing to do with its frequency, similarly, the frequency of electromagnetic waves has nothing to do with the mass.
When we talk about the frequency of oscillations of a mass hanging on a spring is dependent on the mass of the object.
Frequency is the number of oscillations or vibrations unit time and mass is defined as the inertia of the body.
The unit of frequency is \[Hertz\;\left( {Hz} \right)\]and the unit of mass is \[Kilogram\].