Oscar,
When you create a new Couchbase mount, it will usually have the value "type" inserted into the "Document type" field in the Mount dialog. This allows SlamData to present a logical file to you in the UI, and each file will represent one document type.
So if you had document types of Customer and Car, after you mounted Couchbase you could query them like
SELECT * FROM `/mybucket/Customer`
because each document type will appear as a logical grouping or file in the SlamData UI.