Agile describes something quick to change or adapt. An "agile process model" is a software development approach focused on iterative development. Agile methodologies break projects into smaller iterations or parts, avoiding long-term planning. The project's scope and needs are specified at the outset of the development process. Each iteration's number of iterations, duration, and scope are all set ahead of time.
Agile modeling is a technique for demonstrating and documenting programming frameworks in accordance with best practices. It's a set of values and guidelines that can be used in a programming development project.