Question

In a Cartesian plane what is (0,0)

Answer 1

It would most likely be the point of lift-off, judging by the fact that when on the graph, (0,0) is the point of origin.

Answer 2

(0,0) is called the "origin."  It's where the x- and y-axis intersect, that is, where the lines x=0 and y=0 intersect.