Count, sum, mean, median, mode, range, variance and standard deviation for a list of numbers.
They answer different questions. Population values treat your numbers as the entire group (divide by n); sample values treat your numbers as a subset used to estimate a larger group (divide by n−1). Showing both lets you pick the one that matches your situation without re-entering data.
Mode is "None" when every value in your list appears exactly once, so there's no single most-frequent value. If two or more values tie for the highest frequency, all of them are listed together.
Range is just the gap between your highest and lowest value (Max − Min) — it only looks at the two extremes. Standard deviation accounts for every value's distance from the mean, so it's a more complete measure of how spread out the whole data set is.