Risk management is thinking about things that might go wrong and impact the project negatively. There are plenty of examples right at the other end of a Google search. If you are looking for something more specific than what Google provides, please give some more details on what information you are looking for.
There are some real challenges with risk management in practice: 1. Often your biggest risks are things that you're not allowed to publicly discuss (business stakeholders don't trust the IT folks, it's a pet project of a VP, ...). 2. You're often blind to a lot of self-inflicted risks. For example, people mistakenly assume that tradtiional/serial approaches are lower risk. 3. People make decisions, such as insisting on an up-front cost estimate, which they believe to lower risk yet in practice increase risk. I've been on lots of projects where we had to do an up-front estimate, also tried to do risk management, yet we didn't recognize the project risk we'd taken on.
Still, even with the associated difficulties, understanding the source of risk on projects and how to manage/mitigate them is absolutely critical to your success as an IT professional.