Multiple Representations is the idea that a physical phenomena can be explored in many different ways. For example, there is the physical representation which models the system with figures and diagrams, such as a free body diagram. There is also the mathematical representation which uses the equation(s) governing the physics of the system. All of the representations can be used together to help us understand and quantify the physical phenomena.

 

Observe the different types of representations for this section below;

Physical Representations explain the features of the situation in a visual way, often with vector representations of physical quantities overlaid a simple diagram or picture of the situation.
Mathematical Representation uses equation(s) to describe the situation.

A video connecting the mathematics of kinetic friction. Exactly the same type posted in Static section

Graphical Representation describes the situation through use of plots and graphs.

From here

Descriptive Representation is made up enitrely of words or annotations. Think about how you might explain the situation to someone else.

Jill is roller skating in the positive x direction when all of a sudden her wheels all lock up and stop spinning and Jill begins to slide across the ground. As Jill’s motion, relative to the ground, is in the positive x direction the ground applies a force of kinetic friction in the negative x direction.

 
Actual Phenomena could be thought of as doing the experiment. For example, if you're asked which of two runners, with different characteristics of their speeds, will win the race, one way to determine that would be to get two runners to run in the described way and see who wins.