What does extra email account & user account mean?
If you want to invite & allow your team member to use SalesHandy (Track emails & document, send email campaign & add templates), you, as an admin, need to buy the extra user account which will allow you to invite a team member in your SalesHandy account. Once you invite anyone to become your team member, that person needs to open the invitation email and accept your invitation sent via email. That person will be added as a team member under your account.
If you want to use multiple email addresses simultaneously to be able to send email campaigns or emails using more than one email account under the same SalesHandy Account, you need to buy an email account seat.
You can configure multiple email addresses using Google/Office365 & SMTP within your SalesHandy account. Using this extra email account will allow you to send an email campaign from another email address from your existing login.