ADDCOLUMNS Adds calculated columns to the given table or table expression.
Syntax
ADDCOLUMNS(table, name, expression[, name, expression]…)
Parameters
table – Any DAX expression that returns a table of data.
name – The name given to the column, enclosed in double quotes.
expression – Any DAX expression that returns a scalar expression, evaluated for each row of table.
Return Value
A table with all its original columns and the added ones.
Reference Data
https://docs.microsoft.com/en-us/dax/dax-function-reference