The Sanbox File Node will take any file you uploaded into Sanbox, and output it onto your Workflow. You can set a file for the Node to use by opening the Universe Panel and dragging a file from the panel into the dotted space. The following are Read Modes you can choose:
Reads the file as text (Unicode) and outputs a string.
Reads the file as JSON, parses the file into JSON and outputs a structured object.
Outputs bytes representing the file in a raw form.