Agile Development is a organization routine that teams will take part in to struture their progression throughout a project. They can consist of "stand up", "retro", "sprints" and other cermonies. As an example "stand up" refers to the team meeting up at some point throughout the day usually in the morning, where each member can inform the others what tasks they completed in the past 24 hours, what tasks they plan to complete in the next 24hours and whether there are any issues that are challenging or preventing them for completing those tasks.
Using a framework essentially is going to allow you to bypass or streamline certain tasks when building a project which will save time and increase the effiency of your build. Another important aspect of a lot of frameworks is that they allow for scalability, offering tools and practices to help handle the increasing complexity that large projects will face.