An example of a cubic function is y = x^3. Two more examples are y = - x^3 and y = x^3 + 3x^2 + 4x + 5.
In the first example, there is one term with degree 3; this function starts at negative infinity and proceeds toward positive infinity, with an eventual asymptote at some point along the x-axis. The second example has a negative term, which causes the function to flip across the y-axis, forming a mirror image of the first example. The last example is a polynomial with degree 3 and includes four terms in total; these terms don't change the direction of the function, but they do adjust the scale of the function along the x and y axes. These are just a few examples, but there are an infinite number of cubics that can be created to form a function.