I am looking at my Onboarding Settings and would like to understand what the setting for Enforce Participant Languages is for. 

This setting allows you and your hosts, when inviting participants to set the language in which they will see the Supplier Onboarding platform. 

If this is enabled, when you invite a supplier in Supplier Onboarding you will see this option on the Participants tab. 

You can leave this as optional or you can make it a required setting.