Who is asking: Student
"Find the X and Y intercepts" means find the points where the graph crosses the X-axis and the Y-axis. I want to first consider a different equation, y = 2x + 6, with the same instructions, find the X and Y intercepts.
If we now consider your original equation, y = 3x then substituting x = 0 gives y = 0 and thus the Y-intercept is 0. Likewise substituting y = 0 gives x = 0 and thus the X-intercept is also 0. To see why this is true plot the graph of y = 3x.