The root function of After Effects is "Do a, and take b long to do it". It's as simple as that. The tool with which this is performed, is called keyframes. These are essentially markers that say "At this point in time, your value is z", and when you have multiples of these, the program will interpolate the difference in value and time.
So the simple math is saying "Point A(700, 0) at the first frame and Point B(0, 0) is at the 10th frame: Move your object 70 pixels on the x axis and 0 on the y every frame until you reach 700 pixels".