an action potential can be referred as a ¨wave of depolarization¨ down the axon. Explain what you think this means.?

In terms of the sodium-potassium pump, depolarization means the cell's inside environment becomes more positive than usual because of an influx of sodium ions. Prior to depolarization, the cell is negative on the inside (potassium ions) and positive on the outside (sodium ions). This influx of sodium ions, or depolarization, more specifically the interval of the threshold potential, is responsible for starting an action potential.This action potential is important as it is the neuron's way of transmiting chemical signals from one cell to another.

That pronoun, 'you', in the question refers to you not anyone else. If you write what I know then your teacher will think you know more than you do and will not give you the help you may need. Cheating only has very short term gains, if any at all.

I think I don't know.
Neurobiology and immunology are my weak subjects.

You should probably start by discussing "resting" voltage and how that is maintained.
Then you should discuss how an action potential gets started.
Then you should discuss things like voltage gated channels and what the movement of the action potential actually means.
Be sure to mention how this is a one-direction process, and include some discussion of the molecular basis of that, where the ions are, how the ions got there, and how long it takes the ions to get back to the concentrations they had during the "resting potential" time.

Or something like that.