Position, Velocity, and Speed

 Position is a location, using references as a scale on where it is, if we were to put a toy car on a road, we don't really know where it is, but if we put say, a pole on it's left, then we can use the pole as 0, and any number afteer is is positive and any number before it is negitive. 

Location is a "vector", which is a direction of travel. 
If the car were to move, say 225 meters in 3 seconds, and it started at 10 meters, what would be the formula for it? First, we need to know the distance, which is a simple minus 25-10, which gives us 15.
Second, we need to have another value, which is something called velocity, meaning how fast something is going. We know that it travelled 15m in 3 seconds,  so we take the 15 and divide it by 3, which gives us '5'. So it we can confidently say that the car travelled 5m/s or 5 meters per second.

Now we can discuss speed, which is how fast an object is moving. Speed is the distance divided by time, which in this question is 15/3, which gives us 5m/s. 
Keep in mind that these equations are applicable when the object is moving at a constant rate. However, if the object is slowing down or speeding up, they depict the average speed of the object. 

One thing to keep in mind is that speed is just a value; it doesn't matter what direction the object is travelling, it only matters how fast. While distance is for calulating 'distance' and is for when it is travelling back and forth with positive and negative positions.