In Qlik, the dollar sign, $, is used as an identifier to define the relationship between the set expression and the field values or expression being evaluated. The $() syntax is used for dollar-sign expansion, which evaluates the values inside the parentheses and returns the result to create the expression. If the parentheses are empty, as in your example, it means that there is no expression to evaluate and nothing will be returned. Please refer to the post below to see a further discussion of the same
