Online courses.
SaaS.
Software.
Ebooks.
Monthly subscriptions.

Google search "copywriting guide" and take note of how many people charge for stuff.

Those mothers be makin' bank with their PRODUCTS.

...And because they're copywriters (and obviously have decent SEO principles in play), they're probably marketing their products well.

I Will Teach You To Be Rich - try to resist the copy on these landing pages.

Online courses, passive income, Ramit is making BANK.

He's definitely not the only one, just one that I distinctly remember having some ridiculously effective marketing messages in play.

Charge X a month for a subscription to an information hub that you update every two weeks or so with new content (as little as a ten minute video or a long-form guide will do). Make sure your free stuff explains the WHAT—your paid stuff the HOW.

If X is $100.00, 100 subscribers = $10,000.00 a month.
If X is $10.00, 1,000 subscribers = $10,000.00 a month.

Boom, six-figure earnings.

See why the idea is so appealing?

A "product" can be anything that someone is willing to pay for. It's up to you how you decide to present and market it.
Since we're on the copywriting side, "products" can vary from informational guides, how-to articles with high value, case studies, content planning and more on how to write something, up to the actual writing.
You could be selling packages of articles written on demand, for a specific topic, under specific conditions that you get to draw, and that's your "product". Or you could be selling an e-book on how to customize ones article writing services, products and business packages, and that's another "product". It's actually in the hands of the deliverer how to make something look like a product.
Now how does that sound?

Thanks, Chad and Adelaina. I get it now.

This may help you get started. No Product? Start With Bypass Surgery - Michel Fortin

These days, everything can be called a "product". IMO, the easiest way to come up with a product is writing an e-book or a killer blog or newsletter with valuable information that people want to pay for. Charge for subscriptions and, voila!, you have a product. Just make sure that every piece of information you offer is well-researched, valuable and truly helpful for the reader. Otherwise, no one will pay for that information.

Hope it helps,
Typing Pandas