Waterfall development is a fairly rigid methodology that involves a sequential design process, from project conception to initiation, analysis, design, construction, testing and implementation. There is little margin for error and the methodology does not accommodate a re-visit of any one stage in the process once it is completed.
The agile approach was introduced to accommodate the inevitable requirement changes that arise in a project. In doing so, it handles the process incrementally. This allows the team to conduct stages continuously and concurrently, instead of sequentially.
Agile business analysis training is essential to assist a business analyst coming from a traditional waterfall development background to adapt to an agile environment.