Translating a function horizontally is adding up a constant value.
For example g(x) = f(x) + a means that g(x) is the function f(x) translated a units horizontally.
If a is positive the graph is shifted a units upward, if a is negative the graph is shifted a units downward.
Then, the graph of y = 3√x - 3 is the graph of y = 3√x shifted 3 units downward.
Answer: the graph of y = 3√x - 3 is the graph of y = 3√x shifted 3 units downward.