This article describes what whitelisting is. Whitelisting is the practice of explicitly allowing some identified entities access to a particular privilege, service, mobility, access, or recognition.
While IP whitelisting does not encrypt your data the way a site-to-site connection does, it can come in handy if you'd like to save time and avoid the trouble to set one up, as it still limits access to your resources - an entire network or a specific machine or application. Once whitelisting your gateway IP, the resource will be accessible only for devices using this particular IP, that is, connected to the Harmony SASE application.