You can easily get the answer if you search on QT forums or on Google. Still I can give you some basics....
What is Agile?
According to Wikipedia, Agile software development is a conceptual framework for software engineering that promotes development iterations throughout the life-cycle of the project. Simply put, Agile allows your team to identify the most critical features of the software that can be completed within a short time frame (normally 1 to 2 months), and it delivers a complete build with this set of limited features as the first iteration. Once that is done, you can move those features to production or continue on to the next iteration. By breaking the releases into shorter stints, it allows you to gain quicker releases and to capture return on investment more quickly by putting the working (but limited) features into production sooner. This is in stark contrast to the more traditional "Waterfall" approach, where you design all features upfront, code each one, test each one, then move into production. Agile projects are iteratively released to production months where Waterfall projects normally span a year or more before they are released to production.
What is Scrum?
Scrum is process of implementing Agile, where features are delivered in 30 day sprints. Scrum borrows its name from Rugby, where a sprint is the process of stopping play, then vigorously playing until the sprint ends and a new one begins. The same idea applies here, where you define the requirements for a 30 day sprint and work on them with vigor for 30 days without being sidetracked by other things or having things re-prioritized. A specific feature is not recognized as being completed until it is analyzed, designed, coded, tested, re-factored and documented. At the end of the 30 day sprint, most features defined in the 30-day sprint should be completed. If some did not get finished (because of being underestimated), the uncompleted features can be moved to a later sprint. A sprint is considered successful if all the completed features have high quality and can be put into production (or beta) upon ending the sprint.