I was studying things like Declination and such and then we had this topic but I don't really know how to understand it. What is Celestial Motion, what does it mean?

Celestial motion, or celestial mechanics, is the study of motions of celestial objects, for example how the moon moves, or how Jupiter orbits.

Celestial objects usually two different types of motion.
1. The first motion is diurnal , where the whole celestial sphere, and all of the celestial objects attached to it, rotates uniformly from east to west once every 24 (sidereal) hours, about a fixed axis passing through the earth's north and south poleson. It's due to the earth's daily rotation. As well as that, the diurnal motion preserves the relative angular positions of all celestial objects.

2. Certain celestial objects, such as the sun, the moon, and the planets, possess a second motion, superimposed on the first, which causes their angular positions to slowly change relative to one another, and to the fixed stars. This intrinsic motion of objects in the solar system is due to a combination of the earth's orbital motion about the sun, and the orbital motions of the moon and the planets about the earth and the sun, respectively.

I hope I helped ^^

Edited October 2, 201411 yr by Tzurain

To elaborate on Tzurain's points. Based on your reference to declination, I think it is the first item that is most relevant to you. In other words celestial motion is the apparent rotation of the stars around the Earth on a daily basis.