I have graphed this in 3 steps to try and show you pictorially how it is done.
https://www.desmos.com/calculator/aihasozfoa
Only y=x^3 is displayed first.
then click on the second circle to show y=-x^3
now y=|x^3| is a combination of theses because y must be positive.
If you now display y=|x^3| you will see that the graph looks a bit like a concave up parabola.
I have graphed this in 3 steps to try and show you pictorially how it is done.
https://www.desmos.com/calculator/aihasozfoa
Only y=x^3 is displayed first.
then click on the second circle to show y=-x^3
now y=|x^3| is a combination of theses because y must be positive.
If you now display y=|x^3| you will see that the graph looks a bit like a concave up parabola.