Vertical displacement means moving something up or down from where it was before. Imagine you have a toy car on the ground, and you lift it up to put it on a table. This is an example of vertical displacement because you moved the car vertically (up) from its original position on the ground. Similarly, if you move the car down from the table to the ground, this is also vertical displacement, but this time going downwards. Basically, if you move something straight up or down, you're displacing it vertically!