Rapport is a good sense of understanding and trust. If you have good rapport with your neighbors, they won't mind if you kick your ball onto their property every now and then.
If you have rapport with someone, you two communicate with trust and sympathy. The word is often used to mean good interaction between people in different positions or roles such as parent and teacher, teacher and student, doctor and patient, supervisor and worker, or speaker and audience. It is always important to establish rapport with people you come into contact with regularly. Pronounce this borrowed word from the French ra-POOR.