Mean and central tendency
In this section you will get a basic introduction to mean and the central tendency.
https://www.youtube.com/watch?v=CmNgOJYgM5I
In this section you get to know regarding introduction of cosine and the intuition of central tendencies.
https://www.tutorialspoint.com/python_pandas/python_pandas_descriptive_statistics.htm
Overview of descriptive statistics
In this section you will get the answer of the following questions.
What is Descriptive Statistics? Types of Descriptive Statistics? Measure of Central Tendency (Mean, Median, Mode) Measure of Spread / Dispersion (Standard Deviation, Mean Deviation, Variance, Percentile, Quartiles, Interquartile Range), What is Skewness? What is Kurtosis? What is Correlation?
https://towardsdatascience.com/understanding-descriptive-statistics-c9c2b0641291