Phishing is the act of trying to get access to a website by getting someone to hand over their login credentials. Generally, this is accomplished by sending you an email from an account pretending to be an administrator of some sort, and providing you a link to your login page.
Of course, this login page is not really your login page, and once you've entered your username and password, they now have access to your website.
Just as a reminder, d12 Web Design and Development will never send you an email requesting your username and/or passwords. Nor will we ever send you an email with a link to your login page, except when we initially set up your account.
If you ever receive such an email, delete it immediately. Do not click on any links in the email, and do not download any attachments that they email may contain.