SUMMARIZE Returns a summary table for the requested totals over a set of groups.
Syntax
SUMMARIZE(table, groupBy_columnName[, groupBy_columnName]…[, name, expression]…)
Parameters
table – Any DAX expression that returns a table of data.
groupBy_columnName (Optional) – The qualified name of an existing column to be used to create summary groups based on the values found in it. This parameter cannot be an expression.
name – The name given to a total or summarize column, enclosed in double quotes.
expression – Any DAX expression that returns a single scalar value, where the expression is to be evaluated multiple times (for each row/context).
Return Value
A table with the selected columns for the groupBy_columnName arguments and the summarized columns designed by the name arguments.
Reference Data
https://docs.microsoft.com/en-us/dax/dax-function-reference