A workflow is a rule that your record must pass in order to sync. These rules are based on text fields in your system. If a record does not pass at least one of the workflow rules it will not be sync to the other system.
Each workflow allows you to define the criteria a record must meet in order to trigger the sync. The most common action is the process of letting the record sync over to the other system where it will either be created as a new record in that system or will update the existing record.
To get started on creating Workflows, head over to our How To Setup Workflows For Your First Time help article.