An Agile timebox plan is a tool used in agile project management to define the scope and schedule for a project. It is based on the idea of breaking a project down into small, manageable increments called timeboxes and delivering working increments of the project at the end of each timebox. A timebox plan is a flexible and iterative approach to project management and allows for changes to be made as the project progresses and new information becomes available. It helps to ensure that the project is delivered in a timely and efficient manner, and allows for the delivery of working increments of the project on a regular basis.