You can build pretty much anything you can imagine. At first I was under the impression that this was to build contact forms. It does do that but it also builds custom CRMs, rental applications managers, employee managers, office supplies managers, and an unimaginable amount of other choices.
If you can imagine it, you can build it. I still can't believe this is GPL! I do have a $20 Euro subscription, but that is well worth it. I post almost daily in the Forum and I always get timely response.