For the case that n = 0 (before the first run of the loop), x(0) = 1.
For the first actual case, n = 1. X(1) = x(0)*3*n = 1*3*1 = 3.
For the next case, n = 2. X(2) = x(1)*3*n = 3*3*2 = 18.
For the next case, n = 3. X(3) = x(2)*3*n = 18*3*3 = 162.
For the next and last case, n = 4. X(4) = 162*3*4 which I’m not computing. The computer value of x(4) is the value of the product loop.
If that doesn’t help, I could try helping again to rephrase, but I’m not sure what else to add.
If lemmygrad is what op is commenting on, they left it out of the image and caption.