OverviewA Function is a function of an Operator that can be triggered by a FUNCTION Action ("FUNCTION"). Whether an operator offers functions and how they are called and should be used, is documented for each operator.
DetailsTo view which Functions an object has, click right on the object and see if the menu says 'Functions...'. If it does and if you select that item, the Functions Dialog opens, in which you can view and try the Functions and copy their addresses. For more info see "Functions Viewer".
For more information about Actions, see "Actions - Overview".