A workflow is reprecented by steps and transitions that an issue progresses through, thereby defining an issue lifecycle. Steps and transitions can further be customized with validation, conditional access and permission based access to fields to create a setup perfectly tailored to an individual company workflow.
This defined lifecycle usually represents an internal company setup, or reflects a companys team-based structure, and is usually also anchored in a company or teams development and QA guidelines.
The Bug Genie comes with a default workflow called "Default workflow". This workflow cannot be edited or removed, and is used as a fallback workflow or when a project doesn't have a workflow configured. The editing tools for workflow will of course let you copy this default workflow or create a new one to make your own, and everything in other workflows than the builting one can be customized.