This node makes a file accessible to an external caller (for example the REST interface) by providing the path to the file as a resource. It can then for example be downloaded after executing a job that isn't discarded yet. The file has to exist and be located in the current workflow's data area.
This uses node a path flow variables to select which file to expose. To convert the string variables created by some nodes that have not been migrated yet to paths you can use the String to Path (Variable) node. For further information about file handling in general see the File Handling Guide.