When asking if y(x) is equal to the y value I'm told that " y(x) is the y value, but viewed as a function of x in this context, not as an independent variable."
What exactly does this mean? Should I replace with y(x) with 6−x or should I just differentiate the original function normally using implicit differentitation?
Your function is $y=\sqrt[3]{6-x}$ You can differentiate that or you can implicitly differentiate the original equation getting $1+3y^2y'=0$ Since you know $y$ you can compute $y'$.