What is magnitude exactly?
Most physical properties are directional dependent. For example, you can apply a force to a box up, down, at a 45 degree angle or some other direction. To fully know what the box will do, you need to know the direction, plus how big is the force (this is the magnitude). DId you push it really hard (large magnitude) or soft (small magnitude). Velocity and acceleration are similar, I want to know how fast something is going (magnitude of velocity) and the direction. When you use an arrow (vector) to represent these things, the length of the vector will represent the magnitdue, and the direction it points in is the direction.
