What is information?
I'll define it as data, knowledge, and communication (we'll expand on this later).
If you're a web developer, you may need to know what your assigned tasks are. You may have to look up some docs on how to implement something in Drupal. You may have to talk to a client about what they want. In all of these cases, you're seeking or exchanging information.
We create information systems to handle storage, retrieval, and transmission of info. The design of those systems leads to being effective in meeting client and user goals.
Information Architecture is a discipline for analyzing information structures and defining schemas. You don't need to be a dedicated IA to practice it, and learning the fundamentals and techniques will make you much more valuable in communicating with clients and implementing systems.