Duration.Days Function in Power Query
The Duration.Days function returns the days portion of a duration.
Syntax
 Duration.Days(duration as nullable duration) as nullable number 
 • duration: The input, which must be a duration type (e.g., created with #duration(days, hours, minutes, seconds)). 
 Returns: It returns an integer specifies the number of days from the duration. 
Example: Get the Days portion from the duration value.
Power Query M
let
    source = Duration.Days(#duration(1, 2, 30, 0))
in
    source  The output of the above code is 1.