This Tarot reader serves a couple of purposes: it's fun, it helps me practice web design and coding, and it's a creative outlet. At best, it will make you realize something about your own life as you contemplate the cards. At worst, it's no more meaningful than the Monster Maker page.
If you can't afford a professional reading or a real deck, but want something more in-depth, you have a couple of options. You can check out Aecletic.net for a much more robust online Tarot reading generator. Or you can visit the Tarot subreddit for a more personal touch. If you're just curious about the cards, LearnTarot.com is a fantastic resource that's been around since the 1990s. It was among the various resources I used for writing the card descriptions. For a brief history of the cards, check out this article from the playing card company, Bicycle. The Metropolital Museum blog has a bit more on Tarot's history, but for a truly deep dive, check out the print book A Wicked Pack of Cards: The Origins of the Occult Tarot, by Decker and Dummett.
Finally, here's an online version of the guidebook to the Rider-Waite-Smith deck, the deck used by this generator. The RWS is probably the most popular fortune-telling deck in the world, as well as the most influential in terms of Tarot deck design. However, the guidebook is rather coy and can be frustrating to work off of directly.