The collection handle is generated from the collection title. However, if you rename a collection title, the handle does not update.
For example, if you create a collection named "Juices", then update the title to "Beverages", the handle will remain as "Juices". Here's a screenshot of a collection. We can quickly see what the handle is by inspecting the 'view' collection button:
To work around this, you need to create a new collection with the correct collection title but this is tedious.
It would be nice so that editing the title will update the handle, or create a new field in the collection to edit the handle.
A unique, human-readable string for the collection automatically generated from its title. This is used in themes by the Liquid templating language to refer to the collection. (limit: 255 characters)