Sub-processes and Call Activities are essential within a BPMN process. In order to have a refined business process, it is important to add sub-processes.
Thomas, one of our active community members made this video, which can help you understand how Sub-processes and Call Activities in BPMN work.
In this video, Thomas explains using Bonita - How Call Activities and Sub-processes are specified, executed, and when to use them.
If you want to learn more about BPMN check out Thomas's video about the various gateways - explained in a simple and intuitive way. Or you can read about it on our documentation.
Thank you, Thomas!