Yes, they have a very robust database. But what they've been selling to enterprises for at least 20 years is better thought of as ... schema.
When you buy Oracle Financials (or whatever modules / pieces / etc.) what you're buying is "how to set up and run your business." All of the non-physical parts of your business operations are now entities inside Oracle SW (and, as it happens, stored in the Oracle RDBMS, too, but that's practically speaking irrelevant).
Once you're "on" Oracle, or SAP, or whatever, every invoice you send out exists only because it's in that software. The software is your system of record, your single point of truth for your whole enterprise. You might think you are physically a human employee or a box of nuts but if you're not entered into Oracle with a row ID, you don't exist.
So, yeah, Oracle has an RDBMS. But what they really have is the "operating system" or the "schema" of a large enterprise which otherwise would have to rely upon a vast pyramid of specialist operational knowledge (bureaucrats / paper pushers / functionaries) in order to know how invoices got approved, sent, dunned, paid, reconciled, etc., or how orders got quoted, approved, picked, packed, shipped, etc.
(Not meant to sound condescending; I certainly wouldn't have known had I not spent some time seeing Oracle deployed in real life. It was certainly super-instructive for me to have spent a summer during college working for a midsize enterprise on Oracle, in a role kind of bridging ops and IT, and seeing what it really did. No SELECT statements involved.)