The <DirectInput> tag is pretty self-explanatory and executes the stored procedure (in this case). It could also have been a SQL query.
The <Results> element contains a <Result> child element for each field returned in our query. I found this a little confusing at first, but the Name property’s value should reflect the name of the field that is returned from your query or stored proc.
The VariableName property is then used to map the returned field’s value to the relevant variable, and note that we don’t use the “User::<variable>” notation that we see elsewhere in SSIS, but we refer to the scope of the variable with the “User.” prefix. I’m guessing that the change in syntax is because of some other dependencies and/or potential clashes between the Biml compiler and SSIS itself.
This has been a good introductory-level series so far; check it out if you haven’t already.