When you want to do some mathematical operation on two variables (in Excel on to column of data), then you need to note if those two variables are in the same scale or note, if not the end result may not show you a correct value. For example, in may machine learning algorithms, or in multi criteria decision making problems, or when you want to indicate the importance of some factors in quality management systems, you need to take average from some variables, but the average value will be more near to the variable with more data range scales.
In this video we show different feature scaling methods such as Mini Max , Standardization , normalization, scale to unit length along with meaningful example.