This function is only available when connected to a Teradata database.
The non-standard Teradata specific ZEROIFNULL case expression is supported, generating SQL of the form ZEROIFNULL (expression). It must be supplied exactly one argument. When dragging a Zero If Null into a variable, the following tree element is created.
Variable Creation > Input > Variables: SQL Elements pane - Case > Zero If Null

A column, and/or other expression can be moved over the (empty) branch of the tree.
The Coalesce element, which generates the standard COALESCE command, can be used in place of the Zero If Null element, which generates the non-standard Teradata specific command ZEROIFNULL. In Teradata SQL, COALESCE(column1, 0) is equivalent to ZEROIFNULL (column1).
There are no special properties for the Zero If Null function.