Your question is not completely clear to me. I will try to answer what I have understood.
A zoom lens allows the choice of a focal length in a given range. We call zooming in the action of choosing a longer focal length, since the field of view is reduced to a smaller portion of what the lens is facing. Note that the lens might, or might not, appear to be physically longer: the relevant length is given by the optical path. So a typical lens appears to get longer while zooming, but this is not a rule. For example the Canon EF 24-70mm f/2.8 extends in the "wrong" direction: when it appears to be longer the focal length is shorter and vice versa.
So for a zoom lens (as opposed to a so called prime lens, which cannot zoom and thus has a single, fixed focal length) you can choose a focal length in a range, and call it zooming in or zooming out depending if you're going from the shorter to the longer focal length or vice versa.