Here is an example, if I have certain metrics applied, where the comparison of them together, becomes difficult due to the difference in scale, I can apply normalization and normalize the scales
In this graph I have 4 metrics. Since the scales differ between them, they render the graph useless
I can normalize, and this is what I will get:
Here I can make more sense of the data, and compare the trends between the 4 metrics more appropriately.