The contacts for this contact is the contact relationship that has been added to this contact, as per the example below - a relationship to One Plus One was added to the contact Carl Pei.
If you view Carl Pei's contact record, his relationship to One Plus One will show in the Contacts for this contact. If you want to delete the relationship you have to do this from Carl Pei's record not from One Plus One.
- Contacts for this contact
Is a contact of is the contact relationships that this contact is a participant in but is not the owner of. You can't maintain the relationship from here - you can only view the relationship or navigate to the contact on this are.
- Is a contact of