You're a budding developer. You're writing a program. FSF has its lengthy explanations about many licenses, as does OSI. Yet, you want a short and concise answer.
Here's an overview of some of the licenses I consider for my projects, their major differences, and why I pick each of them. I'll also describe how to apply them.
Note: I Am Not A Lawyer, and applying these is at your own risk. Don't apply them blindly, and talk to your employer; you might not be able to decide licensing for your own work. Also, don't use these notes as info on what you may or may not do with code you know to be GPL'd, LGPL'd or BSD-licensed. Read the licenses themselves; these are notes indended only to help in quick decision, not to explain the licenses in great detail.
This is also largely done from memory, without doing proper research right now; it should be pretty correct, though.
Corrections and questions? Put them in the comments section, please 🙂