An affiliation is the connection between a contact and a company. Typically a contact is affiliated with 1 company, but may be connected to more if needed. Each time you link a contact with a company you create an affiliation. If you create a contact without linking them to a company, they still get an affiliation – just a "personal" one. A personal affiliation should hold personal contact details, whereas a business affiliation should hold a contact’s business email, phone etc.
Most items in AffinityLive (Issues, Prospects, Activities and more) are linked to a contact via one of the contact’s affiliations – so it’s important to confirm you choose the correct affiliation when working with a contact record.

The Edit Contact form shows you the contact details on the left-hand-side. These are the details about a contact that do not change between their affiliations (if they are linked to multiple companies).
On the right-hand-side you will be able to update their details specific to each company they are linked to. Click the arrow to hide each affiliation if that makes editing easier!
If you want to unlink the contact from one of the companies listed, click through to view the company and then unlink the contact from the "Contacts" tab.
If a contact has multiple affiliations, you should ensure the main affiliation is correct. Use the Main Business field to select this. This means when you go to create a prospect, issue or contract from that contact record, it will default to the main (or primary) affiliation.