How can i sync or import active directory OU to sharepoint groups in sharepoint online?
You can filter your Azure Connect sync tool down to one or more OUs, but you cannot sync anything directly to a SharePoint Group. The best you can do is sync groups to Office 365 security groups and then used those in SharePoint Online (they appear as "Domain Groups"). But even then, it wouldn't be truly synchronized unless you are paying $6/user/month for "Azure AD Premium" and have the "Dynamic Groups" feature activated. Otherwise, you will have to manage your SharePoint Online group membership separately from your local AD group membership.
