Well you select them, press G followed by the axis which in this case is Y. Move the mouse until you are happy with where they are and then press LMB (left mouse button) to confirm.
This is some unfortunate word choise because the vertices are where they are in 3D-space and if you just switch to the side view (Numpad-3) then of course they are also visible from the side…
I guess you mean something like: How can i build a 3D- face from this front view grid?
YOu can use quad view (CTRL-Q …believe…) to see this head from a top, camera/perspective, front and side (split th full in half to make you own top and side) and then select the vertices you want and move them where you want…