Hey there! I'm happy to help!
If you graph the parent function x^3, you get a function that approaches negative infinity as x approaches negative infinity and that approaches positive infinity when x approaches positive infinity. Applying a negative coefficient negative two is going to invert this behavior, so the end behavior for this new function f will be As x → -∞, f(x)→∞, and as x → ∞, f(x) → –∞.
I hope this helps!