Here's an easy way to think of time. Consider a 1D line. The distance between two points on the line is (obviously) equal to the difference of their x-coordinates, i.e.
$ds = dx$ (or equivalently, $ds^2=dx^2$).
Now move to 2 dimensions. Consider the Euclidean plane (that's the fancy name of a 2D-plane). In that case the distance between two points is:
$ds^2=dx^2+dy^2$
Where $x$ and $y$ are the standard x- and y-coordinates. This is simply the Pythagorean theorem. The distance between any two points is the difference of their x-coordinates squared plus the difference of their y-coordinates squared, with an overall square root. Make sure you understand this, because it's important.
With the expressions for the 1D and 2D distances, you can probably guess what the distance is in 3D.
$ds^2=dx^2+dy^2+dz^2$
and in 4D:
$ds^2=dx^2+dy^2+dz^2+da^2$ etc to as many dimensions as desired.
What relativity does is that it inserts time into this distance equation. In special relativity, the 4D distance between points is NOT the equation above, but rather:
$ds^2=-c^2dt^2+dx^2+dy^2+dz^2$
Note what's special about this. First, time is in the equation. It's on an equal footing as space! Second, there's a conversion factor between time and space, i.e. the speed of light. From this equation when we say one second, we could equally be saying $3 \times 10^8$ meters. That is what time is - it's effectively another dimension, but with a negative sign.
Given this context, your question makes little sense. For example you write:
I know we can measure it but then again what are we really measuring? Aren't we just measuring movement?
Well, if you have a ruler, you can still measure a distance, and once you had a distance, you can divide by the speed of light to arrive at a "time". For example the distance from the Earth to the Moon is about 1.282 seconds (laypeople never use this kind of terminology, but physicists will immediately understand what is meant). Does that count as movement to you?
So my question is if I were to stop ALL motion (even movement of electrons that orbit an atom's nucleus) would I stop time?
But you can't stop all motion. One thing about photons (i.e. light) in a vacuum is that they can never speed up or slow down. Even if you could stop all electrons from moving (and you can't, by quantum mechanics), you can't stop light from propagating, and the universe will change in time.
If all motion stopped for 1000 years and then started again no one would even know. no one would have gotten any older. atomic clocks wouldn't skip a beat. nothing would have happened because time isnt real.
– Stuart Sloan Sep 12 '18 at 23:12