General Statistics is a distribution of individual bytes within the document (or selection). A document or selection is scanned and total number of each byte's occurrences is calculated. The results are then displayed in a table and on a histogram. Descriptive Statistics and Entropy Analysis are then calculated for the resulting data.
General Statistics may be used to estimate the amount of redundancy in a file - if you observe a number of large peaks on a histogram, it means several bytes are more often found in a document than others. This is very typical for executable and most data files. Compressed files, on the other hand, tend to be more “smooth” on their histograms: the number of occurrences of each byte in a file is nearly the same.