Agile is a set of approaches (like Scrum) focused on developing software in an adaptive, efficient and iterative way. Agile values functional software, responding to change, and collaboration among developers and with customers. This is achieved by organizing teams to promote self-organization and cross-functional capabilities.
An important element of Agile is not letting process become more important than solving the problem. Teams are encouraged to identify the uncertainty they face and find solutions to those challenges. Agile is most successful when the entire organization follows it.