On their transaction page, the customers will see your real name and email address (if you have a Personal or Premier Account) or your business name and email address (if you have a Business Account).
Sometimes, the email address associated with a business PayPal account is still a personal email address - and we advise you to create a dedicated, professional-looking email address. If you use G Suite as your email provider, you can create an email alias at no extra cost and you'll receive all emails in the same inbox (eg: all emails sent to your email@example.com will be sent directly to firstname.lastname@example.org, as finance would be an alias for ceo).
After that, you can add email@example.com as an email address used with PayPal, verify it and make it a primary address. All your customers will see firstname.lastname@example.org as the contact email from now on.