Yes, like the description says: "... and the underlying data store". But, it should perhaps say "as modified by the transaction" or something like that. E.g. if you have deleted something in the transaction, it won't show up in this iteration even though it still exists in the "underlying data store", while if you have created something in the transaction, it will show up, etc. I.e. basically it shows what the result would be if the transaction was successfully committed - but if you run it with a transaction where you haven't done any modifications, it will show precisely the "underlying data store".
And just to be precise - "data store" does not in the general case mean "CDB", but e.g. "running" (when the transaction was started towards CONFD_RUNNING). If parts or all of the data store is provided by external data providers, those parts will be included in the iteration. (This is true for all data access through transactions, of course.)