The given polynomial is 
As we know that, the degree of a polynomial is defined as the highest value of the degree of its variable with non-zero coefficients. Also The polynomial is also a sum of cubes
Here the given polynomial is 
The highest degree of its variable with non-zero coefficients is 3.
Polynomial with highest degree 1 is called linear polynomial.
Polynomial with highest degree 2 is called quadratic polynomial.
Polynomial with highest degree 3 is called cubic polynomial.
Hence the given polynoimal
is an example of cubic polynomial.