am looking over a solution to an answer and i dont get some things

Question is

Find the distance from the point A(1,-2,3) to the plane 2x-3x+6z-8=0

Then they picked a random point

P(4,0,0)

and AP=(3,2,-3)

However they also got a vector n=(2,-3,6)

That vector is included in

|AH|=proj n(PA)

=PA*n/n*n |n|

That turns out to be

(3,2,-3)*(2,-3,6) ALL OVER (2,-3,6)*(2,-3,6)

all times sqrt 2^2 +(-3)^2+6^2

My question is how did they get that point n?

Where could that have come from?

Thank you for your help