We include all of the programming and facilities to make your site secure for on-line commerce. There is a fee that must be paid to a third-party Certification Authority , sort of an electronic notary public. This is necessary as part of obtaining your public encryption key.
Encryption is standard practice for commerce on the internet.
It prevents anyone other than the intended party from intercepting the contents of a transmission - particularly credit card information. The warning is pretty impressive so that sites that are not secure won't be accepted by the public for the transaction of business.