The Dummy step does not do anything. Its primary function is to be a placeholder for testing purposes. For example, to have a transformation, you need at least two steps connected to each other. If you want to test a file input step, you can connect it to a dummy step.
The sample below includes a Dummy step, starting with the transformation:
Unfortunately, the Stream lookup step can only read look up information from one stream. The Dummy step is used to work around this limitation: