Here you can type in the name of a previously created customer and it will automatically enter in all their information.
The information on the left will be displayed on the quote as this is used for finding out where the customer is based. This is useful in case you need to mail the quote to the customer.
The info on the right is all the contact info to get in touch with someone related to the job that needs doing. This can be the person who inquired you about the job or a co-worker.
There's also a map at the bottom to see where your customer is located. This is especially useful for cases where you're not sure where they are situated or to see if they're too far away for a job like plumbing or construction, for example.
Here you can see all the info filled in.
If the information is outdated or maybe you need to enter a new contact, there's an enter new one underneath customer address and Contact