AWS services aren't designed for people just learning to program. Beanstalk and other services have billing limits you can set, but those aren't hard limits because they are measured async to keep performance up.

With that said, AWS is notoriously opaque in terms of "how much will I pay for this service" because they bill so many variable facets of things, and I've never really trusted the free tier myself unless I made sure it wasn't serving the public.