CALCULATE Evaluates an expression in a context that is modified by the specified filters.
Syntax
CALCULATE(expression,filter1,filter2…)
Parameters
Expression – The expression to be evaluated.
Filter1, filter2,… – (optional) A comma separated list of Boolean expression or a table expression that defines a filter.
The expression used as the first parameter is essentially the same as a measure.
The following restrictions apply to Boolean expressions that are used as arguments:
The expression cannot reference a measure.
The expression cannot use a nested CALCULATE function.
The expression cannot use any function that scans a table or returns a table, including aggregation functions.
However, a Boolean expression can use any function that looks up a single value, or that calculate a scalar value.
Return Value
The value that is the result of the expression.
Reference Data
https://docs.microsoft.com/en-us/dax/dax-function-reference