The Pipedrive-Klenty integration allows you to create advance automation workflows and eliminate manual task you do to keep your data in sync.
The bi-directional sync is just an extension of that:
With this, you can keep your contacts in sync between Pipedrive and Klenty. Any changes to people in Pipedrive will sync to prospects in Klenty and vice versa.
To enable, go to Settings -> CRM -> Pipedrive