Description
The collections node gives you a variety of options to get data about the collections in your file.
Inputs
The index input can be switched to a Name input with the toggle on the node. This input defines the collection which is returned by the Indexed output.
You can either choose a collection by index (starting at 0) from the list of all collections in the file, or by the collection's name.
Outputs
All Collections: Returns a collection of all collections in your file
Scene Collections: Returns a collection of all collections in the active scene
Scene Collection: Returns the collection that holds all collections in the active scene
Active Collection: Returns the currently selected collection
Indexed: Returns the collection that is selected by the index input, either by index or name

