position
Position tells you where something is. Before you can talk about how a thing moves, you have to be able to say where it is right now, and the honest answer is always 'where compared to what?' If a friend asks where you are and you say 'three metres to the right of the front door', the front door is your agreed starting point and 'three metres to the right' pins you down. Position answers the simple question: where is the object, measured from an agreed reference point?
Precisely, position is the location of an object relative to a chosen origin (a point you pick as zero) using a chosen set of directions (the axes). In one dimension along a line we usually call it x, and it can be positive on one side of the origin and negative on the other. In two or three dimensions the position is a vector, written as an arrow from the origin to the object, r, with components such as (x, y). Position is not just a number; it carries direction, because 'three metres left' and 'three metres right' are different places. Its SI unit is the metre (m).
Almost everything in kinematics is built on position. Displacement is the change in position, velocity is how fast position changes, and a position-time graph is literally a plot of position against time. The one thing to keep straight is that position always depends on your choice of origin and axes: move the origin and every position number changes, even though the object has not moved at all.
Put the origin at your front door and let 'to the right' be positive x. A cat sitting 2 m to the right is at x = +2 m; a shoe 1.5 m to the left is at x = -1.5 m. The same cat and shoe have completely different numbers if you instead put the origin at the cat.
Position is a location relative to an origin you choose; the numbers depend on that choice.
Position is not the same as distance from the origin. Distance is a positive length; position also carries a sign or direction, so x = -3 m and x = +3 m are the same distance but different positions.